Why does he insist on doing improv?

You see it a lot when he's on talk shows. He's one of those guys who buys in to his own hype and thinks he's funnier than he really is.......and when he's on a talk show, he tries to be funny 100% of the time, rather than picking his spots. The really smart ones (like Clooney, Hanks, Gibson).....PICK...THEIR...SPOTS. They play it straight and humble/sincere...but when an opportunity for a joke or some self-deprecation presents itself, they jump on it. Farrell has not learned this yet. He does schtick 100% of the time, and he's not only not good at it....it's actually off-putting!

Chevy Chase is like this as well. His attempt at hosting a talk show failed because people finally realized....he's actually not very funny/clever by himself. He's simply a good "comic" or comedic actor....when he has a good SCRIPT....a good director, and a competent supporting cast of actors. Watching Chevy interview people (or get interviewed himself)....anything where he didn't have a script and needed to try and be funny/clever on his own...was quite painful.

Both Ferrell and Chase were fine in 3-minute skits on SNL.....decent in small bits like that. But that's about it. I don't think either are very naturally funny.

I’ve always hated him and found him completely unfunny

He's made me laugh a lot in some films, but never when he's actually being himself.

I roll my eyes when Ferrell shows up, and he brings with him this bizarre unwarranted hype that surrounded him.

He has comic talent and when he’s given a good script he can be funny (see Jay & Silent Bob Strike Back) but the indulgent improv, which may work on stage, becomes tedious in films.

As someone else said earlier, dude needs to dial it back instead of being ‘on’ all the time.