Updates are expensive and most phones are not. Without a lot of margin, companies can’t afford to provide continued updates. Really low-cost phones don’t get any. More expensive “flagship” phones may get as many as two.

Additionally, the chipset in a phone frequently can’t support newer upgrades, or need significant support/changes from the chip manufacturer to take them. The same cost calculation applies there and the chip companies may not be willing to do it.

Finally, most phones have one- or two-year warranties. There is always a concern that an upgrade could create an issue in a phone that is out of warranty, leading to all kinds of support and liability headaches.

Personally, I think it’s been awhile since an OS upgrade delivered any really fabulous, new features. It’s a lot of moving around the furniture on the surface (even if it enables better performance from newer hardware - which won’t help your older phone). You might consider that your current OS - especially if it’s relatively defect-free - is better than an upgrade that may strain your hardware or have serious bugs.

But I completely understand the desire. There’s something about that new OS smell…