Not at all. I have the Infinity On Wall System (OWS1) speakers and they are only 4.5" thick and they could be about a half inch thinner without impeding on the cones. They sound great. Would I use them for all of the sound production, no, because they don't have enough bass response. If you managed to solve the bass problem by having a sufficiently large sub panel that could move enough air without deep throws, and without distorting the sound, then you could probably do a full thin system without issue. I haven't listened to these particular speakers but I can say from personal experience that thin speakers can sound great.
