The problem is not so much age or experience,particularly in teaching at the ppl level.
It is attitude
You are absolutely correct with that, and I've got to agree with you when you say most young instructors talk about which companies are hiring etc. The thing is though that doesn't mean that they're just there to milk the students out of every hour they can so that they can make their own logbooks look nice and fat.
I can only talk from my own experience, when I was a young(ish) instructor (I was 27 at the time so maybe not the very young instructors you're talking about) I worked at a flying school and with the exception of a couple of 'retired, just doing it for the fun of it types' all the instructors were relatively young (about 22 to 28).
A lot of the time we talked about trying to get airline jobs ( that and 'I'm so poor I kicked a bin down the road, somebody asked me what I was doing and I said moving house' type jokes
) but that didn't mean that we weren't absolutely dedicated to being the best instructors we could be and trying to teach our students the best ways we could.
Something you've got to remember as well is that a lot of the students who are learning are young (and obviously inexperienced) as well and may prefer to be taught by someone they can relate too, i.e somebody who isn't so experienced and comfortable with aviating that they might struggle to understand why a student is struggling with learning something which to them has been incredibly easy for years.
Just as a student who is a little bit older may struggle to accept being taught by somebody much younger than themselves (only natural), a student who is quite young may struggle to be taught by somebody who is much older than themselves. As long as the instructor knows his stuff and is capable of communicating it, then the best instructor for a particular student is going to depend on the particulars of the student.
When it comes to doing 'Advanced Training' though I totally agree that as long as the instructor is capable of teaching in a good way, then the more experience the instructor has the better.
Where some people might try to avoid flying I ended up going down the route of getting into a tiny tin can and taking it up to the sky.
Good on ya for that