Hey, sure, just make up a bunch of lies then, feel free.
So rather than brute forcing anything remotely resembling intrigue via magical mind control, players might occasionally have to dig deep and come up with something approximating cleverness? No offense, but I hardly see that as a bad thing. Magic is fine as a aid, but it shouldn't be the solution to every problem. Mind-control is potent enough as is without having to worry about it lasting for an indefinite period of time. Racing against the clock, as in the one hour time limit of Charm Person, can be a wonderful catalyst for player creativity. IMO, the real magic in this game happens most often when the players don't rely on magic as a crutch.
First, indefinite=strawman. Second, an hour is plenty of time to interrogate.
I understand your point - mind control, mind reading, etc. create special problems for DMs who want to keep secrets. But that aside, we could make similar points about anything:
"Fireball, damage spells in general? That's just a cheap way to do what the fighter should be doing. Why should spellcasters get to solve combat problems with damage spells? Let's make them think for a change."
Also, persuasion skills would seem to present similar problems. "OMG, the rules say so-and-so is just too persuasive, he can get the NPCs to spill anything!"
ETA: the more I think about it, the more I think this "NPCs are going to spill mah secretz!" thing is more aptly described as a DM creativity issue, not a PC creativity issue. Consider the real world; torture, properly applied, will get anyone to spill anything, period, full stop. These are the bounds of reality, not just spellcasting. This also indicates a way forward. The eternal problem for torturers is when to believe their subjects. People who don't know anything will gladly make stuff up to get the pain to stop. Maybe working something like this into magic that supposedly gets the truth out of subjects is the way to fix this DM problem.
Other posters will confirm your bias, but, no everyone is going to agree that one of Dracula (or Strahd, or whoever) should be on par with a single 9th level PC.
And with
whom would they be agreeing or disagreeing, exactly? Because it isn't me.