The only real negative I can see is that the UV will lose efficacy.
The bubbles might reflect things better also.....so who knows...........

Still, the Uv is made to kill things, the CO2 to dissolve things.
You can add these into a filter also, but you lose control of each independent to some degree.

I like to be able to add/modify things to each thing and not have too much going on in one tube or box.

Regards,
Tom Barr