Glass bedding is not only "worth it", it is absolutely essential for someone deciding to participate in what this site is all about.
Being a gunmaker specializing in 1000 yard competitive and "ludicrous" range hunting rifles, I can personally vouch for the necessity of bedding.
All the reasons listed in previous posts are valid so I'll end up being redundant with what I'd have to contribute.
Just know that not all bedding jobs are created equal and you get what you pay for when it comes to stock work.
If you have any doubts, take it to someone who understands that long range bolt guns require attention to detail. Reputations and track records mean a lot here.
I don't claim to be the end all source of knowledge, but I can tell you that rifles I've built have claimed world championships, "real" trigger time in Iraq, and kills as far as 2552 yards on prairie dogs in Wyoming.
I don't know everything, but I like to think I do know what works.
Hope this helped in some way.