You are woefully uninformed. Flashlights have always been lightyears ahead of bike specific lights in LED technology. Flashlights have always had much longer runtimes and much more brightness at the same time. ... ... ...
Bike specific lights have caught up slightly in recent years, but still cannot match the raw lighting performance of flashlights. High end flashlights have their own enthusiast community. There are flashlight online forums, just like bikes have forums. Enthusiast flashlights only have to do one thing: light well. They are constantly updated with the latest LED tech coming out of Asia. Sorry to say this but bicycle specific lights are outdated, over-marketed, overpriced, and poor performing products marketed at lay people. High end flashlights are enthusiast products. Bike specific lights are consumer products. It's the same as the difference between an enthusiast bike and a mass market consumer bike. You're not even in the same segment, and you're not getting the same lighting quality. When you look at the marketing of an enthusiast flashlight, it will tell you the exact LED chip used inside. When you look at the marketing for bike specific lights, this information rarely shared. Ever wonder why? Exactly.
FYI 18650 batteries are the same batteries as used in laptops and portable battery banks. If you open one up, you'll find a bunch of 18650 cells inside. Certain bike specific USB recharging lights have them inside too. All things being equal, you'd prefer the battery to be removable so you can charge them in your own charger, and replace them as they wear out. With bike specific lights, the cells are sealed inside so when they wear out, your light is done. Yet another indication of their consumer product segmentation.
I am not as misinformed as you think. You are so flashlight focused that you see everything, including bike specific lights, through that tunnel. Only one of my bike lights is a unit body 'flashlight shaped' product. All the rest (3) have separate 4 x 18650 battery packs. I would no more want to deal with all those cells individually than I would want a Root Canal procedure. I probably have had a couple of those lights for 15 years. The lightheads anyway. The battery packs are mostly newer. They connected right up to the old lightheads and I can use the older chargers but the newer chargers are more sophisticated.
The light beams are round. I'm agnostic on the issue of round vs shaped beam, but you have to know that you are on the contrarian side of the issue and the majority of cyclists want shaped beams. Quite a few want generator hub power to boot, and that equals very modest overall light output. It's simple physics. You cannot get but so much light out of a 3W Son hub no matter what. But even allowing for some lumen inflation, my newest light the Cygolite 1200 sits on its helmet mount over two MagicShine 808's on the bars and that is plenty of light for this cyclist.
Probably any cyclist, because I have Macular Degeneration and I need a LOT of light at night. Way more than most cyclists that are quite happy with no light at all in the city, and were more than thrilled with the 110L Halogen lamps from back in the day. We don't need bleeding edge light fantastic from Asia because, beyond a certain level of illumination, you are becoming a road nuisance. Flashlights obviously were not expecting to be put on Two Fish Lockblocks and pointed at oncoming traffic in anger. I don't need to be that cyclist that carries an insane amount of illumination because they can.
BTW I know what LED chips are in the lights I use. Maybe you need to see what has taken place in the last 15 years of bike specific light R&D.