I'd argue that yes, you can and should expect people to be willing to explore. Otherwise, it somewhat devalues the opinion – not knowing what's available out there inherently makes the "music today is terrible" opinion invalid because it's a very limited frame of reference. It's akin to me looking at soccer and saying, "well, sports really suck." It's not a complete picture. You know, feel what you want to feel, think what you want to think, but there's never really an excuse to be uninformed beyond laziness and contentedness with the status quo, neither of which is a valid reason to discredit things you don't know about. (And please don't take this as a personal shot – it isn't – I just get very defensive of current music because it's such a common target.)
More exciting, I'll give you. More nostalgic, sure. But better? I'm not sure I can agree with that. Just because The Beatles invented the formula doesn't mean they perfected it.