The spend their days looking at ways to annoy passengers on planes. Well that's what I did for 7 years in the airline industry!

As you are obviously not a thinker:
1) its for your safety
2) where are you going? plane is taxiing and doors not open!
3) sudden stops and jerking are common in maneuvering an aircraft on the tarmac during taxi (so you will fall over)
4) you will hurt someone else
5) there is no where else to go

For reference crew will not open the doors until the captain advises them to by way of turning off the seat belt sign.

In most cases now until the aero bridge is moved into place and the aerobridge operator knocks on the door the crew will not open the door, so this will be a few minutes after the seat belt sign goes off.
So sit back relax and enjoy the service until the seat belt sign goes off.