In terms of the comparison between judgement hammer, turnip, and "magic" Missile (aka Misfire), you can know that what you're doing will cause you to trip. A player makes a conscious decision to forward+B with Luigi. A player also makes a conscious decision to dash. If it's sudden death and you want to avoid tripping too close, use a short hop or a full jump. You can account for tripping (though it is less easy), just like any other random occurrence. I don't see much of a problem with tripping. I have no preference here nor there to it, but I will admit I haven't had it alter my game at all yet.
However, I am actively dashing less, except Squirtle shellshifting. I approch with short hops. I.e. even if I'm at a distance I short hop my way across the platform. You can also approach from the air. If I'm really far away I will dash, and if my foe has something to kill my short hopping I will dash, but I've never tripped big-time before.
All in all: Wanna account for tripping? Short hop, attack from above with a full jump, roll to cover long distance, or even use skull bash, withdraw, rollout, or something of the like as part of your metagame. You still have quite a few options if you never want to trip ever.
(I should note that this is not just a reply to you, but yours is just the post that inspired me to put these thoughts I've had for a long time out into the public sphere. This is a generally directed post. The quote just provides a bit of context.)
Yes, unfortunately there are other random elements in the game, and some characters' games have been boosted from it, although others not so much. There are plenty of Peach mains that can attest to winning a tourney because of stitchface. But these are character specific aspects that you are aware of while playing them, and they're part of the metagame. And they are all very avoidable if you ascribe to Isai's mantra: Don't get hit. This is to say: these things only punish you if you let them hit you. If you never allow yourself to get hit by
any turnips, then stitchface won't bother you. If you never let G&W grab you, and never get hit by
any randomly thrown out judgment hammers, you'll never suffer a 9. This is a simplification, because there are time when you
do, in fact, want to get hit, but for the most part, you can keep to these rules, and these things won't bother you as much.
With tripping though, you have to be constantly aware that fsmashing with the control stick, mistiming a >B, dashing, rolling such that you don't shield first, RARing, Pivot Grabbing, Stutter Stepping, Dash attack canceling, and any other things I may be forgetting are all risky maneuvers. Tripping will punish you simply for doing any of these things. This contrasts with the above random elements in that this doesn't punish you for sloppy play, quite the contrary, otherwise smart moves are quite risky. But let's go to the next logical step by extending "Don't get hit" to "don't put yourself in a position to trip." In effect, doing any of the above now constitutes sloppy play.
Obviously, this means that any tapping motion should be avoided at all costs. This basically means I should not utilize every trick in my bag. I should approach with short hops without even dashing beforehand to gain forward momentum. I should no chase people whom I have just down thrown (I am a ZSS main). I can't approach with RARed bairs. I can't Pivot Grab (which has proven very effective for me, by the way). This list goes on. So we get rid of all of this depth, and are happy. We basically camp, and jump around, and all our opponents will, too, because we're all afraid of tripping. We all play Pit, and the guy who's able to hit the other with the most arrows will win. This is a bit extreme, I realize, but the metagame yielded by such a mentality as what I have just outlined will only be so much deeper than this, and that's no fun at all.
Unfortunately, Sakurai was clever. He made tripping just common enough to be a real nuisance for competitive smashers, but still uncommon enough that the benefit gained by not tapping left or right can't possibly outweigh the disadvantage not doing so puts you at. If the game progresses into the metagame above, some smart-Aleck will eventually show up, dashing left and right and destroying all of us, because he will be killing us enough that every time he trips, it won't matter, because he's so far ahead. What we will have deemed sloppy play makes us look like two-year-olds at breakfast.
So things progress and eventually we find ourselves at a new metagame. This is like the Melee metagame with letting yourself get hit so you can get the bigger hit off. Essentially, we must judge the usefulness of every tap of the control stick, so that if we trip, it will not be too detrimental. This does not mean only tapping when we need to. Fun fact: If you only tap when you need to, the chances that if you trip, you will do so when most vital that you not, will be 100%. So this means that we don't really tap the control stick only when we need to, we do so when we can
afford to. This limits our options, because there will be some options where the benefit they give us does not outweigh the chance that we will trip. And even with this metagame, we risk giving up an advantage entirely because of randomness. These limitations decrease depth by limiting options, and even making good options less good.
This is why competitive players don't like tripping.
You see, you shouldn't think I'm jumping to conclusions here. I've thought about this since Hitaku found tripping to be completely random. I've found that the metagame will be exactly as it is without tripping, we will just have to know what to do when it happens, both to us and to our opponent. I am fully aware of this, and you needn't remind me. And yes, it will be dealt with. However, we are talking about something that punishes someone randomly for playing to their fullest knowledge of the game. Again, this doesn't make Brawl uncompetitive. But it is limiting, and decreases the depth of the game, and many competitive smashers (myself included) have a problem with that. If this bothers you, well, then grow a hide. Some people wanted a game that built on the successes of Melee, and they have a right to that.
I don't mean to sound like I'm making a big deal out of this, but I feel like no one will understand my stance unless I write it out in full, as I have done above. On that note, the above is to be taken as a unit. As such, little nitpicks won't be given heed, because such things only ever come down to semantics, and if you really have a major problem with everything I've said, you can be a grown up and respond with a well thought-out reply, I would hope.
I feel like I should sign this or something...