Canada buying the Meotor?
That's les missiles internally. A Super Hornet or F-15E could carry more even with less stealth. Plus can be a strike bomber.
There's no reason an F-35 can't make use of heavy external payloads for missions that don't require a low observability aircraft. That's in addition to its internal payload. So essentially you can use it the way you would a more conventional fighter, with external munitions, drop tanks, etc - the difference is that if you need low observability the F-35 can do that too, whereas the other aircraft you mentioned cannot, regardless of payload.
Yes, the internal payload might seem small to some people, but it's not as though a typical strike mission would be flown by a single aircraft, you can expect a package containing multiple F-35s along with supporting assets, and the internal payload doesn't look so small when you're dealing with more than one aircraft. Likewise in an air to air combat scenario, four AMRAAMs might seem light on, but again you're not dealing with a single aircraft, but several. And because of the aircraft's datalink capabilities, if one F-35 detects hostiles, all the other F-35s know about it and can cue missile shots from that sensor data. So it might seem like a low number of missiles per aircraft, but the total available missile shots within the battlespace is going to look very different. Secure datalinking makes a very big impact.
Essentially the F-35 can do the same kind of things as a typical fourth generation multi-role combat jet, but it can also do things the fourth generation jets just can't compete with - wideband low observability, more comprehensive sensor fusion, better battlefield networking capabilities, and so on.
