I think it just makes for a better story that Harry always seems to be struggling financially.
It means he has to be more creative in problem solving and recruiting allies etc.

Considering he now lives in a top of the line, all the bells and whistles, castle courtesy of Marcone.
If he also had practically unlimited funds he would be a far less sympathetic or relatable character.
Whatever the problem, friends in trouble, need some hired help, run a castle, research...Just throw money at it.
It would become boring quickly.

I have to agree that Harry being celibate/lovelorn has become a little stale. He deserves some uncomplicated action.

And I like Lara as a character. I think the books where she has featured have been among the better ones of the series. As far as bad guys go she's OK, on a par with Marcone imo.

And at least she is a fully grown female.
It's better Harry finding himself attracted to her than in previous books where he was noticing how "hawt" the young Molly was, or that other white vampire college girl who was dating Bigfoot's son.

We already have Thomas as a practically celibate, sex vampire, Carlos messed up after the Molly episode, Butters seems to be the only relatively good guy who's having some fun.

Love the books and series, just think it's a pity the gap between books has become so long.