I suppose I'll be the dissenter here--I enjoy restoring tools. I'm also an indebted student with no money so a new LN or LV is not within reach anyway...but even if I did have the money I would spend some time restoring old tools. Sure, I'd love a low angle jack plane and I would be more selective with my restoration project mediums but restoration is its own pursuit for me. I get a kick out of the aesthetics of these old things, the knowledge that I'm using a tool made 100 years ago, and the idea that I kept one more valuable item out of a trash dump or some hoarder's basement. It provides a fun vehicle for me to learn about the old toolmakers and manufacturers, and how craftsmen did things a century or two ago. And as much as I would like to support great companies like LN or LV, I also believe that increasing recycling and/or decreasing consumption are usually good things so putting an old tool to work also fits into that aspect of my worldview. It probably also helps that I like a lot of the skills involved in restoration but there are plenty of enjoyable mechanical skills in woodworking as well.
Now all that said, if I didn't enjoy history and care about saving relics from junkyards the appeal would diminish quite a bit. If my focus and desire was entirely centered on working wood then tool restoration would be a nuisance. And while I have learned a lot about how planes work by restoring a few, I'll echo Archie's sentiment above. You can shorten the learning curve quite a bit by knowing what a well tuned plane, saw, etc. is supposed to feel like. It can be hard to determine whether deficiencies are in my own skill or in some poorly-functioning aspect of a tool sometimes. With a new LN/LV tool you can't misplace the blame--it's all on you!
One thing I'd advise to anyone interested in tool restoration is to be selective in your restoration candidates. Since I started out with such little money, I'd often pass up a decent plane for $30 because I found a slightly crappier one for $15. That $15 savings, more often than not, translated into hours more time in restoration and a less refined final product. Some things should be deal breakers. If something has a lot of deep rust that will leave pitting after its removal, you should either be fine with the pitting or you should suck it up and fork out the cash for a better project. Grinding, sanding, or draw-filing pitting out of metal isn't enjoyable nor is it much of a learning experience. It simply isn't worth the often minor savings up front. There are definitely great deals to be had out there, and I've gotten lucky on some tools in great condition for $10-15 or so, but those deals take a lot of time and effort to find. You won't find them on ebay or in an antique shop--you have to put in some hours digging through flea markets and estate sales. So if that kind of thing isn't worth your time then finding old tools becomes much less financially advantageous.