Can flow of gas be too strong to ignite in oven?
I would speculate that the MIXTURE of gas and air may be off, in the "too much gas" direction. There are lower and upper limits of the gas to air mixture beyond which the mixture will not ignite (too little gas to light, or too little oxygen from air to light.) Removing the oven floor may provide just enough extra outside air to allow it to light.

Check the color of the flames - if they are more yellow than blue that's a pretty good sign the mixture is too rich. There is normally some sort of air control on/near the burner inlet. They are not too prone to move of themselves, but they more often get plugged up with dirt, hair, or spiderwebs. However, it may need adjusting if merely cleaning it does not solve your problem.