The speed of Wireless AC isn't about being able to saturate a super fast 10Gb fiber connection or something folks. It's about file transfers.
For example, I have a NAS (Network Attached Storage) in my home that stores video and photos that I use. I use locally attached storage (USB 3.0 currently; contemplating an upgrade to a Thunderbolt RAID array) for 'working' data, and other data is stored on the NAS. Sometimes I need to move data from the USB 3.0 drives down to the server, or vice versa. Before wireless AC, I had to use ethernet if I wanted to get it done in a reasonable amount of time. Despite the theoretical max, 1.0Gbps ethernet is still faster than 1.2Gbps Wireless AC in my cases (since I can saturate Gigabit ethernet and run right at the max, but can't come close on Wireless AC); but nevertheless, Wireless AC is finally fast enough that it's reasonably useful even without running an ethernet cable.
Losing performance on Wi-Fi is definitely a problem for some users. However, those users are probably less likely to be using the base model 13" MacBook Pro. I'm sure Apple figures, anyone doing content creation and working with lots of data stored on a network, are going to at LEAST be using the Touchbar 13" model with it's faster CPU, et al; and more than likely, the 15" model. Now I'm not justifying this at all. There's never a good reason for less performance. Just saying that I can't imagine many users at all 'noticing' the difference, and those that would, probably won't own this model.
The 13" Base model has become the "Macbook Air", heck, Phil Schiller even said so. I'm curious of the 13" TouchBar model will include the faster wi-fi.