Out of universe, any – especially magical – "Get Out of Jail Free" card (a sort of Deus ex Machina) can be overused as a plot device. If Rowling used it to solve every small problem, the books would suffer, and the characters wouldn't "develop" to overcome obstacles using their own resources.
If you accept the out-of-universe justification for limited use, then in universe – despite the OP not wanting to talk of the room's limits – then we have to assume that it does have limits, and those limits are (reasonably) high: you cannot use it just because you fancy an ice-cream!
An answer to the no-longer directly linked question What are the limits of the Room of Requirement? includes (emphasis mine):
[The Room of Requirement] is a secret room within Hogwarts Castle, that only appears when a person is in great need of it.
This is echoed on the Room of Requirement page on WikiBooks (again, emphasis mine):
Dobby the house elf tells him [Harry Potter] about this room, describing it as, "A room that a person can only enter when they have real need of it. Sometimes it is there and sometimes it is not, but when it appears, it is always equipped for the seeker's needs."
I cannot remember (but it has been a while since I read the books) of any instance of any of the main characters trying to gain access to the room and failing, so it's unclear
whether they tried and failed to use the room for "lesser" needs, or they simply realised that it would only work for "great need", and never tried. However, I seem to remember a scene (at least from the films) where someone (possibly Filch, possibly Umbridge) was trying to follow Harry in to the room and it failing to open. If so, then this could indicate that it wasn't just personal need that mattered (the need to catch Harry didn't override Harry's need to not be caught).
In summary: the room does have limits, fairly high ones. Either the main characters knew these limits and didn't try to push the boundaries, or any failed attempts weren't included in the narrative.