Wouldn't people complain about not being able to clear the tower more? I can see arguments like "it increases the gap between F2P and whales", " the rich get richer", or something along those lines.

FYI I am one of those people who got stuck at F100. I don't have Specter Tenebria or Dark Corvus. I might be able to try the Tamarinne Falconer Kluri Iseria DPS comp, except that I don't have Song of Stars.

If the total reward for clearing F91 to F100 were like 25 galaxy bm, 15 MolaGoraGo and 20 mil of gold (distributed to each floor, with more reward at higher floor), I think the problem would be way worse. Sure the reward is (probably) worth the effort, but people who can't clear the tower would be way more behind than those that could.

How I cleared 95-99 (might not work for everyone, but maybe it can give you some idea for team composition via characters in similar roles): https://www.youtube.com/watch?v=GpYa1Y-x0LI&list=PLGVjhByDqqoCKKe4N8e7smUT980Dtn4F5

tl;dr - Better reward at top floor to justify "effort" might put those who coudln't clear the tower further behind than those who could.