50-100 in PotD already are casual floors. That was part of what gave it longevity. First it was having just 1 to 50 available. Then the other half came out with 50 more floors to keep people busy.

It's above 100 that requires a fixed party but IIRC the party has to start at 50.

I don't really know how they could make a roulette, though. Whole idea behind them is progressing one set of floors at a time and losing your progress if you fail and a roulette would let someone skip around in floors instead of doing that build up. Though it would be nice for being able to see those sets of floors nobody is ever running.