One of Luigi's weaknesses in Smash 4 was his traction, but it could be mitigated with good powershielding.
Did these changes hurt Luigi?
Nah, most-likely you're going to be able to have Street Fighter-style parry shenanigans like
Perfect-Shield > uSpecial. uSpecial's sweetspot hitbox seems to be a
lot bigger now (at least horizontally), and being able to powershield in the
middle of blockstrings is going to be a huge help to you. Remember, in older Smash games dropping your shield took a pretty long time, generally too long to drop in the middle of a string and pop again between moves.
Now, if people decide to go crazy on your block they risk you dropping block for a potential kill at decent percents. In fact, if you were to down somebody on a high platform, jump and waveland into it (since we can do that again!), you can simply start shielding, and if they do their wakeup attack you can perfect shield it every time for a free shoryuken from a high elevation. I think Luigi has secret top-tier platform tech chase setups.