let me put it this way:
it is used by so many altcoins because it is supposed to be used by so many altcoins. it is designed to do exactly that and nothing else.
in other words your question is like asking why so many people use Firefox to browse internet instead of doing somethign else with it.
Over the last 2 months I've heard so many people talk badly of ethereum but the point is that so many altcoins who use the ethereum technology have great success. For this reason I asked the question.
In other words Firefox if it was not good nobody used it...