Yeah it's all a matter of taste obviously. Personally, I don't think the Sierra interface was ever bad.. I loved typing in stuff as I felt it gave more freedom in some cases (and some funny responses too). And the system they implemented with Kings Quest 5 (icons) was pretty good and it didn't clutter up the screen much either.
And I think it's a good thing they made many sequels!
Of course, humour is highly subjective so that can't be argued.. but I think Sierra did have some pretty funny games