Especially where the Klingon and romulan involvement with the Dominion War and Deep Space Nine is concerned. It's all the freakin' way on the other side of the Federation from where Star Charts shows them to be. Makes no sense, even if you try to rationialize it by saying that Klingon abd Romulan teritory "wraps around" Fed space "above" or "blow" the 2-D plane shown on the Star Charts maps. That would add a lot or territory to either of those entities, but yet every single place ever mentioned on-screen is shown all the freakin' way on the other side of the UFP from Bajor/DSN/The War.
Except that STSC uses a "small Federation" theory (pretty much necessitated by later DS9, which established that Bajor, beyond the Federation border, was only days' travel from Earth). So the core of the UFP is only a couple of hundred light years across, meaning that "all the freakin' way" isn't really that far.
Besides, many nations throughout history have waged war very far from home. Places like Korea, Vietnam, and Iraq are all quite far from the US, oceans away, but Americans still fought extended wars there. So I don't see why it should be a problem that Klingons and Romulans are able to wage war at a considerable distance from their home territories.