Exactly.
I wrote this last year criticising the current state of Mac hardware.
https://medium.com/@Pier/the-problem-of-osx-hardware-in-2016...
Even though you don't need lots of power, there's plenty of solid and valid reasons why others might.
Moreover
1. latency is low enough that people are playing triple AAA video games on AWS for a $1/hr.
https://lg.io/2015/07/05/revised-and-much-faster-run-your-ow...
2. Sure, that's a good reason. It had better be spewing out lots of data, though, or again, you might as well process in the cloud.
3. Being able to access your workstation via airport wifi at all is actually a benefit in this case, unless you intend to wheel it around like a suitcase.
Did you walk out of a 1980s time warp or something? The workstation in this case carries 1TB of storage and weighs 3.5 lbs. (And it still has wifi in case you need that).
Regarding your number 3. For a lot of this, we are talking about devices like the MacBook Pro line. Not huge workstations.
On the other hand, outside of ML it's not like many software developers need to upgrade to a new GPU every (other) year and current processor trends show very little performance uplift between generations to upgrade - once Apple finally gets 32GB of memory in the MBP most developers will be set for many years.