throttle and nozzle
As someone paid (on occasion) to cogitate on matters pertaining to the control of STOVL aircraft, I'd like to add to John's reply. It's my opinion that from the outset of the P1127 the designers had in mind that firstly they were in the warplane business and secondly that to make a VTOL (as it began) one they should depart from established sound warplane practice to the minimum extent practicable. So as John says, the throttle lever followed established practice of being a chunky bit of kit that fell easily to hand and had room for various important switches. Various other reasons (not least doing things in a manner perceived to be above all reliable given current proven technology) resulted in the nozzles being controlled by a mechanical lever. An electrical switch could go on the throttle lever (and later on of course it did in the nozzle-nudge system) or, as with the Yak-38, on the stick-top (although it has a mechanical conventional-flight/powered-lift selector inboard of the throttle too), but a mechanical lever had to realistically go elsewhere. The nozzle lever had to go close to the throttle, because at several stages of flight right after making a significant input with one there is a need to make one or more inputs with the other. It would also clearly help if the two levers were radically different in feel, to reduce (but alas, as history has shown, not eliminate) the odds of moving the wrong one. So big throttle meant smaller nozzle lever. A small nozzle lever outboard of the throttle would be awkward, as would any lever not big enough to stand well above the throttle. So as the smaller lever, the nozzle lever had to go inboard.
It's worth also pointing out that there's a handy little shelf outboard of the throttle where some some hydraulic pressure gauges live. In the hover this shelf is well placed as a hand-rest, allowing subtle movements of the throttle lever (try using your computer's mouse without resting your hand on the desk/mouse-mat - doable but not easy to be precise). If I dig around at work (fall-out from office moves permitting) I may be able to find out when this shelf was added. If it was there from the outset then it would also have influenced the original choice of lever arrangement. An outboard nozzle lever would be tucked away under this shelf, or have to be on top of it somehow. As John says, the Harrier (less so Harrier II) cockpits are rather cosy, so I doubt an ergonomic solution with the levers swapped over would fit.
F-35B has a really chunky throttle grip (so chunky we had to have a bit cut off to fit it in a Harrier cockpit). It has no nozzle lever at all.