multirole vs dedicated, single seat vs dual seat

it seems that starting from the 3rd generation of aircraft, we see a tend leaning towards the development of multi role aircraft over dedicated aircraft, especially in the 4th generation.

it can be argued that a multi role aircraft will not be as good as a dedicated aircraft in a specific role, especially when it comes to pilot training (training a pilot to be a master of a single role versus one who has to learn many roles but does not strongly excel at one). It can also be argued that such multi role aircraft are much more complex to build and take a longer time to integrate its various components

However others argue that while it may be more expensive than a dedicated aircraft.. it is cheaper to own and operate one multi role aircraft rather than two dedicated one, especially during peaceful times.

what are your thoughts on this issue?

Since the issue reflects on how much a pilot can handle, it also brings up single seat versus two seaters.. there’s been a tendency for two seat strike aircraft to distribute the tasks (as it may be too difficult for just one person).. as we see in certain F-16, M2000, Su-30, F-15 models.. and a drift towards buying more 2 seaters than planned (Rafale and Typhoon).. however the F-35 seems to break this trend, reverting back to a single seat.. has the work load on the F-35 reduced so much that its role can be done with ease by one pilot?