I just assumed the reason for no igniter in the oven is due to how hot it gets in the oven. Unlike a BBQ where the ignitor is under the unit and out in the open air, the oven is enclosed and the burner is right there. The underneath section of the oven gets hotter than the cooking compartment of the oven. How much heat can an ignitor take before it burns up?
Same for your stove and your hot water heater, the ignitor is not enclosed with the flame.
For you that have installed one yourself, has it lasted?
The trick to lighting an oven is to hold the lighter flame under the thermocoupler so it lets gas flow to the burner, not just the pilot light - then you are lighting the burner where a lot of gas is flowing out, but you also have to turn the oven to the Low setting. You can decide if this is safe for you or not as I am not interested in opinions of course. I do this all the time.