No, this is not the case at all. My 2010 MacBook Pro with only 802.11N connects to my WiFi network @
240 Mbit/sec from the other end of the house. My 2014 MacBook Pro with Wireless AC connects to the same network at between 700 and 900 Mbit/sec from the same location.

...
MacBook Pro's support channel bonding (up to 3 streams I believe).
TVs, AVRs, BluRay players, etc. only support single streams and can only do 150Mbps no matter what your router says on the box.
Do you have an iPhone 5 (or earlier)? Go tell me how fast that is on your network

. iPhone's are single stream devices.
Or if you have an iPhone 6, go tell me how fast that is when compared to your AC MacBook

.
Most devices do NOT support channel bonding since it requires multiple antennas.
You just happened to pick the one device that supports channel bonding to make a meaningless example.
By the way... what are you talking about on your other point too?
Most of the big ISP have announced plans to deliver GigaBit internet to the home in 2015 / 2016. There are at LEAST a dozen areas in the country where you can get GigaBit internet to the home for < $100.
HINT: Wireless AC doesn't have the capability to go at GigaBit speeds.