If someone feels more comfortable using non renamed then you should have no problem with it. A lot of people have moved on to 474+ now, but just look at the majority still using 317 because it's what they know and are used to. The same thing goes for non-renamed to renamed clients.
OT: This, if anything, should be a snippet. Though I'm sure it's more client related.
No, people use non-renamed clients because they don't know any better. They use them because Bluur's client is non-renamed, and many inexperienced people use Delta sources. This isn't always the case, I know, but this is true for the most part.