First of all, I grew up around tractors that didn't have all the safety bells and whistles the current ones have. That requires a different set of behaviors to maintain a safe working environment. No roll bar, then you hitch the tractor so the load doesn't tip it, and you don't drive on slopes too steep. No seat safety switch? Then you engage the brakes, take it out of gear, and disengage the PTO before hopping off, or shut the engine down altogether.
Secondly, the more parts you have have, the more systems you have, the more points of failure you're going to have. Frankly, I don't know of ANY tractor company that doesn't use the cheapest doggone switches for their seat sensors. Which means they're one of the most common parts failures and replacement items. Which means it's deliberate, and a money maker for the company.
Third, that seat switch has the potential to shut your tractor off in the worst possible place and the worst possible moment. Like crossing a busy 4 lane highway and have it fail right in the middle, or crossing a stream, plowing your driveway, or putting down a tree, or it rolled against and pinned somebody against the wall. Think of your own example. Point is, you need to move it and it's going nowhere without a replacement switch, and in some cases you aren't able to get around the tractor to go get the switch at all!
Fourth, consider who's driving your tractor. Kids, then yes, you want a seat switch. Spouse or multiple other users, then you want a seat switch. Just yourself? You can train yourself not to ever need it.
After the third time I had a seat switch fail on my tractor while I was out in the woods, I cut that dratted thing out and spliced around it. I've never regretted it. And I never will. Although if I do sell the tractor for an upgrade, I'll have to replace the switch then.
