I think it's OK to dive into the Q ecosystem as long as you do it eyes wide open.
1. The system is small but complete. Zoom lenses are available that cover from wide to tele. Everyone always wants more lenses - who doesn't? - but I don't think you'll find yourself lacking in focal length. Quality of the lenses ranges from OK (02 zoom and 03 fisheye) to excellent (01 prime and 06 and 08 zooms). Personally, I don't lust for any new lenses in the Q ecosystem.
2. Ricoh hasn't updated the Q in quite a while. A lack of updates shouldn't mean anything one way or another. Scissors, pencils, shoes, and beach towels haven't been updated in a long time as well along with ground beef, milk, and cucumbers. I still enjoy all those things today as I did yesteryear.
3. The sensor tech is dated and limited compared to today's more modern units. That doesn't mean it's bad. Just be aware that the Q is not for low light, fast focusing, action shots. Get a DSLR or something else if that's what you're looking for. It's a creative tool. Use it properly and you'll be rewarded. Don't be afraid to experiment either.
4. Speaking of experimentation, this camera nearly begs you to experiment and "take the shot". What's the worst that could happen? You miss the shot? It's blurry? So what - erase it and try again. The camera is an underdog but still wants a chance to succeed. It's so small and compact that it go with you unnoticed in places where a DSLR would be an elephant in the room. The Q with an 06 lens fits in the palm of a hand - and that's with a lens hood! Try that in any other system.
5. Going further with experimentation, the Q is meant to be fun to use. You should enjoy pressing that shutter button. You will use a fun camera more often than a boring camera. If a Q tickles you the right way then go for it and forget what other people say. Don't let the tech specs dissuade you.
On paper the Q is an expensive camera when compared to other systems. Don't be shy to look at other systems and understand the alternatives. I think the u4/3 system is going to rule the world of "small" one day if it doesn't already. It won't be as small as a Q but maybe small enough for people to easily take where they want to go. You have to really want the quirkiness of a Q to justify it. I have a Q and a u4/3 system. The two compliment each other quite nicely.
You have to really want the quirkyness of a Q system to buy into it and enjoy it. Otherwise, it will sit on your shelf like an old book. Buy what you will shoot.