RAF Fighter Jets: What’s the point?

Forgive the overly simplistic title, and the similarly simplistic ramblings below.

In the last 2 decades if not more, most war fighting has been carried out in a ground support capacity, where we get some “fast air” types to roll on in for a “non-kinetic attack” and then let off some ordnance towards the bad guys on the ground.
I’m wondering what the point is in having hugely expensive assets (Tornado/Typhoon) carry out such warfighting, when in the South Americas, they use Super Tucano’s in the Hunter/Killer role.
Yes, sure we need QRF, and there’ll always be a need to have a few aircraft under maintenance, but do we need over 100 Typhoons?
I know I’ll get flamed, but I really think for the recent warfighting we have done needs a cheap, low speed, long loiter type(s), to combat the threat from a man waving an AK47 around.
Over to you guys….