That's ridiculous. Things are not fine the way they are.
155 to 170 is too big a gap for such a small weight. And a 20 pound gap between 185 and 205? Ridiculous.
Welterweight and middleweight should be re-aligned to 155, 165, 175, 190, 205. That would accomodate more fighters stuck between weight classes. For example, Yoel Romero is one such fighter. He's clearly too big for 185, but just a bit too small for 205. The result is him depleting himself too much to make weight, and missing it sometimes. A 190 weight class would see fewer middleweights miss weight, and also fewer middleweights fighting undersized at 205 (because they can't quite cut to 185).
Similarly, you've got fighters like Colby Covington and Nate Diaz that are too big for 155, but probably a bit too small for 170. 165 would be a perfect weight class for them.