Because they worked too well?
Seriously, that's like asking why computers nowadays are so cheesy, or why cars nowadays are so complicated that you can't fix them in your back yard, or why machine tools nowadays are made so that you have to have a degree to operate them.
Gravelys are simple, solid, get-the-job-done machines. They weren't engineered to have super duper safety features, or to be way fuel efficient, or any of the other characteristics that you get with modern lawn gear. I used to buy Honda and other modern mowers, but they broke every few years. My gravelys beat the socks off the new stuff, but I'd be hesitant to turn somebody loose on them who wasn't willing to take them on their own terms.
I have a 1928 Model A Ford. It strikes me as being very much like the gravelys. My Camry has more amenities, is more comfy to drive, quieter, gets better fuel economy etc. But the A is tough; I can take it in rough terrain, or over ugly roads, run it on fermented kumquat juice, fix it with nothing but a screwdriver and pliers. It also takes some fiddling to get it started, the brakes are wierd, shifting takes some getting used to, etc.
If somebody wanted to build a Model A today, it would be easy enough technically. But nobody would buy it for what it would cost to build, and they'd gripe about lack of "modern" features. Sadly, the same is true of the gravelys.
Seriously, that's like asking why computers nowadays are so cheesy, or why cars nowadays are so complicated that you can't fix them in your back yard, or why machine tools nowadays are made so that you have to have a degree to operate them.
Gravelys are simple, solid, get-the-job-done machines. They weren't engineered to have super duper safety features, or to be way fuel efficient, or any of the other characteristics that you get with modern lawn gear. I used to buy Honda and other modern mowers, but they broke every few years. My gravelys beat the socks off the new stuff, but I'd be hesitant to turn somebody loose on them who wasn't willing to take them on their own terms.
I have a 1928 Model A Ford. It strikes me as being very much like the gravelys. My Camry has more amenities, is more comfy to drive, quieter, gets better fuel economy etc. But the A is tough; I can take it in rough terrain, or over ugly roads, run it on fermented kumquat juice, fix it with nothing but a screwdriver and pliers. It also takes some fiddling to get it started, the brakes are wierd, shifting takes some getting used to, etc.
If somebody wanted to build a Model A today, it would be easy enough technically. But nobody would buy it for what it would cost to build, and they'd gripe about lack of "modern" features. Sadly, the same is true of the gravelys.