some people feel that their lives do not revolve around programming, that there are other interesting things like traveling and child raising that take a chunk of their ever precious and limited time.
so it's not to say they aren't interested, but rather lack the time to dedicate. therefore, it helps if the company they work for can offer a little time to learn new things.
I'm talking about developers who when offered a chance to learn something new at work reject it, usually while getting pretty defensive.
My current hypothesis is people get so used to internally defending their neglect of the skills that earn them travel and shelter that when the opportunity arises to actually get paid to improve, all the reasons they normally use prevent them from even doing that.
I thinks there's truth on both sides of this. There are many blub programmers that know some narrow scope of Java or C# and a little SQL and that's their whole programming life. This is true regardless of age.
so it's not to say they aren't interested, but rather lack the time to dedicate. therefore, it helps if the company they work for can offer a little time to learn new things.