And what do you do when you have a linear level without an overworld or hub? See, you guys really have a lot to learn from pattoo. Even if his levels are quite poorly implemented and he gets a lot of things wrong, he gets other things right that I rarely see in other levels, one of which being these breather screens. Now, to be fair, he absolutely overdid it here, but it's not much worse than non-stop difficulty ramping, which just causes player fatigue. This level would be much worse without those screens.
Even the main game has breather screens—look at Green Grotto, Merge, or Wheeler's Wormhole—and it's not to the detriment of the levels! In fact, they serve an important purpose as the lowest points on the game's interest curve, basically how engaged the player is. It would be easy to assume that more engagement is always better, but it's not the case. Every time that is attempted, it only ends up being draining and frustrating, ironically unengaging.
This level's main flaw isn't the fact that is has no-obstacle rooms, but rather that it doesn't use them well. The main problem is that he doesn't have anything to build on, so the interest curve is always too low. It's also overly-long, which doesn't help matters at all—everything past the third level or so could get axed, or just merged into one.
In short, don't mistake this level's use of filler as a reason to avoid no-obstacle rooms. They really do serve an important role in level design, and can take a level out of the gutter. Without breather screens, you can only make utter crap.