He never should have been forced to answer a question about his personal affairs in the context he was- which is why they did it.
But also- you shouldn't perjure yourself to hide it. As ultimate executor of the laws of the United States... you need to expect better from him.
I don't recall all the details about Clinton, but the part that I always thought was problematic about it and why I thought it was totally political - had to do with questioning and topics that had nothing to do with being the president. I think we need to have an ability for anyone to have a personal life separate from the job. As an electoral issue, sure. I don't think being a good person has mattered electorally maybe ever in the US, so I kinda doubt anyone's sexual predilections or infidelity matters - see JFK, Clinton and certainly Trump. I tend to think removal from office should have a higher bar than "you cheated on your wife" given all the context. I don't know why Clinton didn't plead the 5th, I'm not sure if that was allowed, but I again do feel like context matters.
That seems somehow different to me than official acts - Clinton's BJs weren't official acts as president. Trump (or his allies) has spent a lot of time delineating Official Acts from Personal Acts, and TBH I agree that is important in my views. I might disagree with how they're classifying things, but the concept seems important and was lost in the Clinton Impeachment IMHO.
Trumps phone call with Ukraine at least wasn't a personal social call if I recall correctly - it was an official white house call between leaders. I agree with you, it didn't seem impeachable to me, but I do think it was materially different from getting placed in a corner over an illegitimate (to me) line of questioning.
And that's my problem - Trumps stuff is ?mostly? around stuff like the quid pro quo or yes, the insurrection. It's direct governing stuff directly affecting the rest of the government. Clinton getting a BJ, or Trump's peccadilloes in the bedroom, aren't.
I think the other way to think about this is - we kinda expect politicians to lie, both for the bad reasons of image, but also for national security reasons or stuff being classified. Up until Trump, no one expected a president to challenge the peaceful transfer of power. The day someone tries to Impeach Trump over Stormy Daniels or the like is the day I'll also say that's totally politically driven, and really not that relevant.
Hell, I'll even say, Trumps not wrong that there's a lot of political attacks against him. Like you said with Clinton, that's part of being a President or Former President. The Government hasn't been above getting people for "lesser crimes" in a politically motivated way when they can't get them for "the real crime" - think Al Capone. And I'm sure some of the cases were purely stuff like that. Doesn't change the fact that they were still crimes, and I probably wouldn't have opposed bringing a perjury charge against Clinton once his term was down - though I also probably would have thought it was a bit of a waste of time.
It's very clear to me that if we survive this second term, Trump in general has really highlighted a lot of issues with the American system, that's for sure.