A plane that does "everything" will do nothing well.
I agree. I do not think that you can build such a plane. The costs would be very high.
what we need are Dedicated Air Superiority fighters, Ground attack fighters etc. I Present as evidence the A-10 warthog, one of the best Aircraft in the Inventory, but I couldn't' dogfight if its life depended one it, that is NOT what it is designed to do!