Support extra JPQL comparators in method expressions

The method expressions is currently supporting primary JPQL operators while it seems feasible to implement other operators like "In", "NotIn", "StartingWith", "True", etc. 

I tried to add some of them and seems they works (of course thanks to the way they've been designed so that it's easy to extend them). I'm just curious if there is any technical consideration/limitation preventing us to have these operators or is it because they were never been requested?