Do LTE speeds make a difference in real world usage?

I've seen a couple of Verge reviews now that spend a lot of time pointing out that LTE is not available on a particular device (the Nexus ones specifically). But I have yet to see a justification of why we need 15-20 Mbs on a mobile device. I can certainly see that you'll get a better synthetic score on something like, but what about real world usage?

Here's some typical high bandwidth cases:

Youtube HD content: Typically 3-6 Mb/s for 1080p content

Data Heavy websites: The render time is going to be the limiting factor at a certain point. I think that will be less than 3 Mb/s, but can't be sure.

Downloading large files: This case will yield a measurable difference, but do I really want to download a 1.5Gb movie over my 5Gb data capped mobile plan?

I'd prefer to see actual use cases where the bandwidth gets in the way, rather than just that a slower standard is supported. And on that note, I'd like to see T-Mobile HSPA+ compared to Verizon LTE rather than ATT HSPA+ to ATT LTE. T-Mobile is the one company that really made an investment in HSPA+, and it is the logical choice to run these unlocked Nexus devices on. I get that Josh can't get coverage in his apartment. But Josh's apartment does not typically represent the whole of the USA. Have the guys in Chicago or the West Coast give it a try and give us the numbers. This "Josh Hole" reminds me of the San Francisco ATT problem with the iPhone. Everyone talked about how awful the iPhone on ATT was, but I think it was magnified even further by the fact that most tech bloggers were in a place where ATT was struggling, and might not have reflected the wider network.