Upvote:2
I have heard countless examples of people getting multiple entry visas in other situations or even without asking for one but in principle they are intended for regular professional or family visits, not as a convenience for tourists (cf. article 24 of the Schengen visa code). It's also intended for travellers who have proved their reliability and this is only your second application. So the decision appears to be correct and there is not much you can do to force their hand. Even if it wasn't, appealing is hopeless and not an option for something like that.