OK, so I was like you for years when I was just flying internationally on long-haul flights with rare layovers (and if there was a layover, there were hours in between flights) so I always just hung out, went for a pee and got on the plane as late as possible.
However, these days I'm doing a fair amount of Canada/US short distance flying which means I'm only taking carry-on luggage and I'm usually having to get off at airports to get another flight with a short period of time between landing and taking off.
So because of this, I found if I get on early there is enough room for my bag in the overhead compartment.
Also, if I'm at the back of the plane sometimes it can take 20 minutes for the plane to exit as every fucker spends 15 minutes trying to put their coat on before they leave the front and so I'm then spent running through O'Hare trying to catch my connection that AA nicely booked 30 minutes after their other flight landed and that was 15 minutes delayed.
So...yeah. It's quite stressful sometimes, especially when it's a work trip and I dont have the luxury of booking my own stuff.