The F-35B
is better than the jump jet and its decedents. There are a lot of reasons why, but the biggest is the fact that it is a fifth generation compared to a 3.5-4th generation aircraft.
Does it make sense to roll a STOVL concept into a stealth airframe? No. It really doesn't. The Turbofan (which was an
interesting choice to begin with) has to go into what would have been internal bomb bay space. Otherwise the aircraft would not have been stealthy by default.
This runs you into another problem. Bombs on external pylons are not stealthy, and since you took up most of your internal space with the turbofan, you
have to mount your weapons on the outside, if they are of any size or number.
Why they didn't go with an easier to maintain and only marginally less useful low-observable airframe, and pair with an aggressive electronic warfare escort. Like how the Navy did with the Super-Hornet/Growler combo, I do not know.
There is another design flaw, while it isn't causing problems right now, will severely cripple the fleet in the future.
You see, in order to get the weight low enough to that they could take this conventional takeoff aircraft, and turn it into a STOVL, they had to cut
very aggressively.
Effectively they halved the useful airframe life due to accidentally removing too much frame reinforcement. This is the cancer that is "concurrent engineering."
This
should be fixed on late block F-35Bs, but earlier block aircraft will either have to be retired, or sent in for an even more expensive rebuild. I don't envy that choice.
_
TL

R: Is the F-35B better than the Harrier aircraft? Yes. Is it as good as it should have been? No, and that is a bit of a travesty.