Given your respiratory history '68 you're probably better off vaccinated - generally the flu jab is around 70% effective, it differs year to year although how the health profession arrives at that number I'm not quite sure.

For Covid - probably the same as you're likely to get milder symptoms when you have some degree of protection. I'd also strongly recommend you seek antibiotics whenever you get a chest infection if you're more susceptible to pneumonia - that said, I had pneumonia once when I was around 6yrs old but never had anything respiratory since then but you're asthmatic too.

If you're a fit and healthy guy who can shrug off minor illnesses & the asthma isn't worsening (ie controlled but with higher medication doses to control it) then your risk of complications from flu/covid is worth looking into further with a GP who has some experience in that field for a fully informed view.