Is it a design flaw if the Enterprise-B, Enterprise-E and Titan (Picard) also have the impulse exhaust going right into the bussard collectors?
What, are you new here?
Not a design flaw rather a design improvement. The high quality waste stuff in the impulse exhaust is directly recycled back into the ship's matter collection system.Someone a while back pointed out a design flaw of the impulse engines going right into the bussard collectors would probably not be a good. So I'd likely add a deck to the neck, / redesign the engines a bit.