Beyond the basic "still works after all these years" vs "unnecessary complexity" is a bit of nuance. I prefer the look of a thumb shifter, but there's a place for both on my rides.
Rapidfire shifting is great for really rough riding. When you are bouncing around at high speed, it's tough to tell if you've found the gear accurately without it. When properly tuned, bang the button and get the appropriate gear. I use it on my more "modern" aluminum bike (2007). The older steel steeds get classic thumbies. Thumb shifters are great for obsessive fiddling on quiet rides where you can hear the ticking and make proper adjustments to get it straight.
Potentially getting a bike with trigger ones has me weighing up pros and cons of each and asking whether I will get used to triggers or to get thumbies right away.
I did use triggers back in the day and from memory did not like that it was only one click to drop, but iirc you could 'sweep' the up trigger, for lower gears, multiple shifts in one go. Is that right and still the case/the normal operation of most trigger shifters?
As someone else aptly put it in the thread I like how you can 'dump the whole cassette in one sweep' if you want to though that alone is probably not much of a benefit in practice in that I am more likely to want to sweep multiple shifts up than down, when reaching a sudden incline. The other way round, when going downhill, as I am not in a hurry, there is plenty of time to click through down one by one.
I am more someone who just likes ambling cycles on small roads or light off-road gravel or such, so the benefit of shifting on rough ground would be moot to me. I was thinking the trigger ones (or gripshift) might be marginally safer since you don't have to take your palm off the grip for those. I was thinking in some cases that might be a safety feature if some hazard suddenly came across your path mid-shift on roads for instance. Could that be considered a viable risk?
Probably the time when you are moving the hand highest off the bars is when you are going slow, uphill, anyway as the lower gears for the back relate to farthest pushes on the right thumbie. Most of the time, in the middle of the cassette changes, you would be able to flick with the crotch of the hand while still gripping the bars.
As for the front, if you did use the biggest ring often that might be a factor as you would be moving fast then by virtue of using the big one but I do not remember the last time I used the big chainring, except last ride just to check the chain still shifted to it and summarily put it back to the middle.
As mentioned in previous reply, friction trigger style would offer best of both worlds. So do they not exist or so uncommon as to be unattainable aside from some DIY solution?