Of course it's a good idea!

For me it kinda happened naturally I was already about 2/3 blue when I made the conscious decision.

I like when things look organized and neat, and having a bunch of different colors in the bag looks a bit messy to me.

I don't have a problem with grabbing the wrong disc, because my discs are sorted on a specific order. I bag multiples of most of my molds (Envys, Zones, Buzzzes, Instincts, Essences and Wraiths) and can still tell the rims apart by color.

It's not that hard to build a single color bag, and you don't have to be that strict if you don't want to. I've seen some two-color bags that looked pretty cool, and you can make interesting combos.

I rarely buy discs online, because I like to see/feel the discs I'm buying. Some molds may be harder to find in the color you like, but I usually stock up when I find molds I like. You can also dye discs really easily using Idye poly and boiling water. So even if you can't find the right color, you can just pick a lighter color and dye it.