Unless you have like 40 years of nothing in real life ahead, how would you ever finish it if every battle turned into a 30+ minute tactical battle?
You're aware that games with manual battles have the option to auto-resolve, right? For minor skirmishes that's an option people use a lot in Total War too.
And it's not like Paradox games have that many more battles than Total War games on average.
Yes, a balance is possible between strategy map vs tactical map, because some games do get it about right. eg XCom, HOMM 3. Though on auto-resolve, it is good to have. But I can't help thinking that if a game is designed such that half of it can be effectively switched off, then that indicates a design problem.
In Dominions, I'm not sure whether the emphasis is on the campaign map or the battles. As I said, I liked the way Dominions solved this problem. Haven't played it for years, but as I recall, you don't have to watch all the battles. It is basically an auto-resolve, only much better as you do get to set up your army and give orders. It's a neat solution and not too unrealistic (yeah, I know its a fantasy game!). But the idea of you as the Big Commander, basically laying down the top level orders then watching your underlings obey them - or not quite do as you expect. Best of all, it's quick, which in Dominions is essential as the campaign map is so clunky and needs so many clicks to do anything, it is slow going.
I'd be happy if Paradox games adopted a similar concept. The combat has, for me, always been the weakest part in them. Give the army high level orders "defend/attack/hide etc" then watch in a quick battle like Dominions could be neat if well executed.