It's a stupid renaming system. So we'll be at version 30 in 5 years. How many programs really use that. It seems when most get to 10, then they start naming programs version 2011, 2012. Because they appear that they are getting too high up there, but internally they say 2011, but have like 16.5.12, that's when things get really confusing.
I know this version 4 is a major overhaul, but nothing wrong with calling the next major one 4.1, then 6 months with another big upgrade 4.2. I don't mind the 4.0.10 numbering systems. People can figure out with Google, which would lead them to sites like this that if next one was 4.1.0 was major overhaul from the previous they could figure it out very quickly, they don't need to have a version 5. Yes it's psychological for many, but when you click the update, or it pops up Mozilla could even have a Bing, Yahoo, and Google link icons bringing them to those search pages with the keywords filled in for the reason to switch to a nice newer feature rich update.