Long analysis, although the real kicker for Spinning being easier is Team Preview. You know 100% now whether they have a Ghost to block, and whether they have a Pokemon to comfortably take a non spin attack as you initially get in.
I wouldn't say that. Regardless of whether or not the presence of a ghost is known, Rapid Spin can be costly to carelessly use. If a team seemingly needs hazards, then, logically, it must have a way around Rapid Spin. Let's say your opponent revealed that their Tyranitar isn't bulky, but rather, Scarfed. Now, in addition to that, say your opponent carried the following Pokemon alongside Tyranitar: Lando-T, Forretress, Nattorei, Latias, and Stoutland. Clearly they're going to be making use of multiple layers of hazards here (Stoutland really loves them, and that could be Roar Latias), but don't have a spinblocker. Now let's say that you just double switched your Forretress into the opposing player's Tyranitar. Would it be safe to go for the spin at this point? Of course not. Even ScarfTar can afford to drop one of its moves for Fire Blast, which makes it a superb Forretress lure and Starmie trapper. Knowing this much, you'd still have to play that Forretress safely, as if that Tyranitar is carrying Fire Blast, you just lost your spinner against a team that excels with hazards up. The mental effect here is similar to the mindset influenced by the presence of ghost on a team that's clearly stacking hazards; you don't want to give your opponent that kind of--well, any--momentum and must try to play around said blockade. Team Preview does help a bit, I won't deny that, but it's always been ideal to get a feel for your opponent, as well as the team they're using, before going for a spin.
Nobody would (or should) resort to Foresight (in OU) to get around spin blocking so idk why you mentioned that.
Say that to the nice chunk of the tour players using Hitmontop and even Blastiose to great effect. Having a guaranteed spin is valuable for any team, and it's not as if the aforementioned FSpinners don't have any use outside of that. Hitmontop is a superb [CB]TTar check, and is a nice sponge for U-turns, which gives it nice synergy with more... defensive teams. I mean, Intimidate in general is always nice to have in higher tiers, softening up the abundance of physical attackers, consequently lessening the amount of pressure physical sponges / walls have to take. Similarly, Blastiose is capable of checking a few offensive threats, namely Gyarados, and can be equipped with one of two phazing options and the almighty Scald.
Dragonite without SR up is pretty beast too. If SR didn't exist, I think every team would carry him. I don't see why not, since the other team is literally screwed if they guess the wrong set or don't carry multiple checks.
Having frequently lurked and played in the SRless ladder, my opinion on Dragonite in this particular environment will remain the same. Dragonite is still too slow, not to mention that it needs a buffer for switching in to retain MS. Even Volcarona isn't hot **** thanks to the rather high population of stall teams. If anything, legendary, flaming, beautiful ALPHABIRD (aka Moltres), is a bigger threat than those two.