In their infinite wisdom....

Speaking as an engineer: we don't design to make it hard to work on, we design it to be as cheap as the boss wants so that we can keep our bloated salary.

Bolting an engine to sheet metal? I'd prefer to put weld or clinch nuts into the sheet metal - or even weld a bracket on so that the motor mount bolts screw into the base rather than into the engine.
For 1, if you strip threads in the engine case the engine is trash - expensive replacement. For 2 - more durable connection.
In reality, it never goes that way. Good welders cost a fortune, and tapping a hole is one of the more expensive operations. A big sheet metal part with weld nuts? Forget it - would add $15 to the assembly once you account for the scrap rate because the minimum wage worker doesn't give two ***** about a proper install, and the higher waged guy is 'too good' to install weld nuts and so does it at 1/4 speed. So instead we fire the welder and just punch holes and tap the engine case - because the engine case is likely in a mill already, and the 'cost' to tap it a tool change and 2 mins of machine work and the robot is never 'too good' for his job. About $2 to tap those holes, Last I checked $2 < $15, so it's a no-brainer. (all $ figures are made-up and exaggerated, but you get the gist).

Most people these days don't even own a wrench, let alone a socket set. Why would I care to make it easy to work on? For the 1 out of 100 that have a clue - sucks to be you! But the assumption usually goes that if you can fix it, you will likely improve it and make it easier to repair next time - but I'm not going to give up 20% market share due to a $60 higher price as a result of 'better' construction no one actually cares about. Karen is just going to buy the one at the top of the list sorted by "price low-high" anyway.

Those engine mount bolts should have probably been hit with a thread locking compound. But if you've priced 'patched' screws in the past 5 years, you'd find they're stupidly priced because the patching companies know they have you by the short-hairs. It also plays hell with automated assembly equipment, since snugging torque and final torque wind up very close to one another. Liquid thread lockers are a *****. Either the assembly smears goop all over everything, and spends $200 per shift in thread locker, or they don't apply enough and things fall apart anyway. Teaching a robot to "squeeze a little bit, no not that much" is also too hard for the snot nosed nerds to figure out - so we just tap holes in aluminum slightly undersize and hope they stay together. Need to remove a bolt? Well, it won't stay tight the second time! Thread locker time.

Oh, and freight costs a goddamn fortune. So it's not going to ship it fully assembled. No, it will ship boxed within it's own parts to save on packing materials and then they let the blue haired freak that couldn't pass his drug test put it together in the back warehouse with stamped-out wrenches that will never reach the proper torque for those bolts. That freak can't change a tire, but they're good enough to trust with assembling equipment that could maim you if assembled wrong. But that's why they have insurance - to ensure the retailer gets paid if you get hurt, but don't expect help with your recuperation.

I could go on for ages... if you want equipment made to be worked on, buy commercial grade stuff but be prepared to pay through the nose for it. If you're running a business with it, the higher costs are a no-brainer. If you're just clearing your driveway a half dozen times a year? Be prepared to spend a couple days every year re-fixing it. Oh, and don't buy craftsman LOL. Their engineers design stuff to look like tools - none of them actually work in my experience. So far, I've had the best luck with stuff from Honda. Even if the equipment is so-so, their engines just run and run and run. Even if the power rating is low, they out-work all the other junk 10x.