-----"Rather than "solving problems abstractly and in theory" and being pretentious intellectuals (which is fashionable), what should philosophers and soc. scientists do? In order to actually help and do something useful for the society?"
Let us assume here that by 'philosophers' you mean professional academics. If you look you'll see that they do not solve problems 'abstractly and in theory' or in any other way. Not one solved in two millennia of trying. To be helpful to society philosophers must solve problems. Then they will be able to explain how the world works to the lay public. Until then the public is at the mercy of a thousand unhelpful ideas with no way to choose between them.
It is a vital issue. At present religious and scientifically-minded people are allowed to believe anything they like because philosophers have let then down. The result is a chaos of temperamental and idiosyncratic world-views that are chosen on a whim and clash wildly with each other.
Society needs a healing vision and it must come from philosophy. But the profession has given up on understanding philosophy. It has found that it's approach does not work and assumes this means that no approach works. Gloom and despondency is endemic and even university chancellors are now questioning its value.
The solution would be to assume that the reason this philosophy cannot solve problems is that it grounds itself on false assumptions. One of these assumptions states that rational philosophers must reject mysticism. This self-inflicted limitation on thought and research comes at a high price. There are no unsolved problems in the philosophy of the Upanishads but this is from the Land of Woo. Best to to stick to defining problems and avoid solving them if the solution is 'not-invented-here'.
Mine is a jaundiced view of academic philosophy and it will grate with some but really, is it not about time it moved on? What sort of discipline is it that can be proud of defining problems but unable to solve any? How could it ever be useful to society?
Idealism comes in various versions and flavours. In philosophy its basic claim is that everything is an idea. In the social sciences it may have other meanings but they have little use in philosophy. At its simplest idealism is simply the opposite of materialism, a mind-only instead of a matter-only theory. It doesn't work in this form but is much closer to something that works than materialism and so is popular among philosophers even in this simple subjective form.
A more sophisticated form of idealism would be 'Absolute' or 'Transcendental Idealism'. This is 'non-dualism' and the philosophical basis of mysticism or the Perennial philosophy (Buddhism, Taoism, etc). Naturally it is largely unexamined in professional circles since it solves problems and is useful to society. It is not easy to find a pro who know much about it, the consequence being that the lay public is almost entirely unaware of it.
As for the question, what should philosophers do 'to actually help and do something useful for the society?", my proposal would be that they should do philosophy. There would be nothing more useful they could do. Society is in desperate need of a healthy philosophy department. How we create one I have no idea other than to keep chipping away at the layers of prejudice, temperament and group-think that afflict the current one.
I feel that sites such as this one, which is excellent, hold the key to initiating major changes in philosophical thinking across society because they bypasses the intellectual road-block that is professional philosophy. Perhaps one thing philosophers could do to help society is to support sites like this one.