If we were talking pre-2006 I would agree with you. iBook, PowerBook, iMac PowerMac and you had speed bumps each year.
Since 2006 we've have the Mac Pro, MacBook Pro, MacBook, MacBook Air and some specialty Macs like the black MacBook. Each model gets offered in multiple GHZ speeds with different GPUs. The whole shebang has even further been stratified by referring to the models as early 2011, or late 2014 or what have you because Apple releases more than one model variant every year. Then Apple adds in the retina Macs - which are supposed to be better than the earlier models.
If you are a current Apple user this may make sense to you and it may be "relatively straight-forward and easy to understand," but I assure you that as a user coming from the PowerMac era or as a new customer it is not easy to understand. Perhaps it may be if you stick to one specific year when looking to buy, but overall - no. It's a confusing mess. And a lot of the problem is that the models all look the same.
Tell me what the physical difference between two aluminum MBPs are where one is Core 2 Duo and the other is Core Duo? You can't. You have to look at the model number.
I like Apple, but I'm sorry, their model offerings just got very large and confusing post 2006.