Not true at all.  Many PS3 owners I know with multiple consoles have opted for a PS3/Wii as it gives you probably the best combination of exclusives, etc.   I myself am included in this crowd, although I do also own a 360 / Gaming PC.  

You don't sell 75 million consoles when all these big mean HD console owners rip on how lame motion controls are.  Most people ripping on the Wii probably own one themselves.  It's not the concept of motion controllers (The concept is excellent and fueled 75 million Wii's to be sold.)  that people dislike or rip on. 

It's the performance, the function, the software and the softwares assumed target audience that has more 'Hardcore' gamers up in arms and annoyed/upset with the Wii.  To a lot of people (Myself included) the Wii has been very under-whelming in terms of it's performance in games and it's functionality. Whether this means a lack of 1:1, a lack of games supporting motion plus, games that waggling is a viable tactic, etc.

The software that has been good for the Wii has rarely seemed to be good BECAUSE of the Motion Controls (Mario Galaxy, Twilight Princess, SSB Wii, etc,etc). And the software that is good with motion controls is limited (in my eyes because of the 'type' of games they want to make not because they don't / won't work.)

Also, there has been plenty of debates on what is 'mature' or 'adult' or whatever.   But the fact remains that many people above a certain age would prefer playing a game that feels more geared towards them and this usually means not rescuing some purple onion after being given instructions by this hamster dog thing.  This doesn't mean blood and gore and swear words necessarily either, but just something that has more mental meat to it.   A lot of Wii games in my opinion seem to be shallow on that side.

Make no mistake about it, people of all backgrounds of all levels of ownership are excited about HD-Motion Controls and always have had some level of interest in them.   The implementation has been lacking so far and with Kinect / Move there is a new ray of hope that the implementation (along with graphical fidelity) will improve the entire experience.   Time will tell.