On the other side, I don't recline the seat to create more space for myself. I recline it to alleviate discomfort from the absurdly upright default seat position.
(Since the seat is level or slopes slightly upward from back to front then the pivot point is at the back of the base of the seat. Since the legs are sitting on - i.e. above - the seat, then the knees have to be above the pivot point and reclining does indeed remove leg space.)
Disclaimer: I'm over 6' with long femurs and have had exactly this situation happen to me on a flight. When the person in front of me reclines my legs do not fit in the remaining space, even if I'm sitting all the way back in my seat.
I understand the economic rationale airlines have for separate seat classes, but at the same time that rationale irritates me because I end up having to pay more for something that is entirely out of my control (genetics).
But a normal "feet on ground" sitting position doesn't work if someone infront of me reclines their seat.
If your bag is taking up all of that space, you are doing it wrong.
Reclined seats can also make laptop use difficult and some people don't check what is going on behind them before blasting their seat backwards which can be disastrous if you have a drink on your tray at that moment.
I love to recline my seat and stretch out a little but I rarely do so since it is so annoying to the next person. The only time I recline is on long-haul flights when the lights are out and I can see that the person behind me is clearly sleeping. Even in this situation, I recline just enough to give myself some lower-back relief.
But IMO it should be enough that it intrudes into my space, which is already at an extreme premium. It doesn't have to be useful space, I'm already cramped and you're making my space smaller. Please don't.
Think of it this way: my house has 8 foot ceilings. I'm only 6 foot tall, so I could lower my ceilings by almost two feet and not hit my head. But it would certainly impact my comfort level inside my house.
In fact, with my MBP sitting on the tray when someone declines, the top gets caught where the tray fits into. I have seen my screen bend slightly when someone reclines quickly. I expect to get a laptop destroyed that way at some point.
Even when I do recline (not often), I do it slowly so if the person behind me is using their laptop, they're not surprised.
So it's pretty inconvenient.
Whenever I fly for work I usually pay the extra money for a better seat personally.
I typically don't recline my seat on a plane, because in most cases it makes my ride less comfortable to be behind someone who reclines.
It is NOT OKAY.
It is the kind of thing previous generations would start fights over when a merchant was so blatantly screwing them over.
Or my other choice is be (more) uncomfortable.
Here's a hint, pay for first class. That's the equivalent level of service and price range that previous generations received (inflation adjusted).
The seat will literally sit on top of my knees the entire flight, full weight. It is more than an "inconvenience" it is damn painful.
It also made positioning the laptop a little trickier, but it was totally manageable and just a price you pay on an airplane.