You really want to get into a semantic discussion? Because claiming that having a tactical camera option is "different gameplay" is going to accomplish just that. Same with the ability to pause combat. You know what I meant, so let's move on.
I love semantic discussions. How does the tactical camera not constitute a radical gameplay difference, and why would they bother to design the entire SP campaign around the existence of tactical camera if MP was informing SP?
As for your second point, I could argue that you have the inability to prove that the changes weren't due to accommodating MP. Why do I have the burden of proof?
Because you are the one making definitive claims, and I am not. If you only wanted to say that it's possible MP influenced SP design but that we don't really have enough info to make that claim, then we don't disagree in any meaningful sense.
These features were present in both previous DA titles, and suddenly they aren't. MP wasn't present in both previous DA titles, and suddenly it is. MP = no pausing so hotkeys suddenly become ultra-important, and consoles have a limited number of hotkeys. I am not making any leaps here by asserting that they have to work around these facts when developing the gameplay system (which is the same for MP and SP).
This is why I'm not letting the whole "gameplay difference" thing go. In Mass Effect 3, SP had paused radial menu with ability selection and MP did not. In Inquisition, SP has pause with tactical cam and MP does not. Therefore, it's clear that BioWare is historically fine with SP and MP playing differently. To support your claim that the ability limit is because of MP, you'd have to provide some reasoning why BioWare would draw the line at ability limits when they 1) did not do so in ME3 and 2) are fine with Sp having pause and tactical cam.