I think your sentiment is great whirly and nice to see, but the problem does not just lie with pilots no approaching other pilots it is often the attitude of the flying school.
Its fine when a more experianced pilots turns up and offers to fly with someone if they are using a school aircraft but when a private owner offers the same experiance they are positivley frowned on for "stealing" the punters from the school. This then leaves the inexperianced flyer in the position of peeing of the school and flying with the private owner which could turn out to be a limited opportunity or stay in the same situation. This has happened to me on a couple of occassions.
To be fair there are a few schools that make an effort to retain the interest of flyers, Northants School of Flying as one example make sterling efforts to retain flyers with a very busy schedule of flyouts throughout the year to interesting places. We attend everyone of these as a private owner usually in the twin. This gives the newer pilots the opportunity to see there are more things to achieve and to share ideas. The only problem for a lot of people with these type of flyouts is that they happen during the weekend as the schools want to preserve the weekend revenue line. Sensible business practice but restrictive to a lot of people.
Other schools I have encountered are just interested in your money and once you stop spending you are virtually ostracised. This does not do much for retaining new flyers!