That's fine - but not all iPhone5's have the same bands either - still they're still called the "iPhone5" (with small ways of finding out exactly what model you have if you really care).
They should call the model one thing and just have small variances in model that are descriptive (e.g.: MOTOFONE F3 vs. F3c - the latter is CDMA).
Having random numbers with substantive differences in features that aren't "cumulative" just seems egregious and anti-consumer.
I've never paid much attention to model numbers when trying to buy a phone; for feature phones I usually just walk into the carrier-of-choice's shop, filter by form factor, and then look at which one has the right price point. Most of the time, a lexicographically larger model number means "bigger, better, and more expensive", which is enough of a heuristic if there are only ten models on display.
Having lots of models at different price points seems crazy for Apple, but it makes sense for just about anyone else making cell phones. Flooding the market with tons of choices at different price points happens in everything else we buy, from CPUs to cereal boxes to jeans.
Plus, if they change a part inside (say, update the CPU, or cut the RAM), the home-tech-support person in me would rather that they change the model number, than sneak in a nontrivial "Rev. 2" update. (This was a big deal with the WRT54G, when people were buying them and flashing custom ROMs that only fit in older models with more memory.)
They should call the model one thing and just have small variances in model that are descriptive (e.g.: MOTOFONE F3 vs. F3c - the latter is CDMA).
Having random numbers with substantive differences in features that aren't "cumulative" just seems egregious and anti-consumer.