Steve, Luke and Chris made great points.
Since I started collecting T206's, my main objective has always been to get as close to completion of the set (minus the ones I know I cannot afford) and hopefully acquire at least one example of each back. But- the priority to me is the fronts. Now, to add a little excitement- people (like me) will examine the card to death looking for any type of printer flaw or anything that might make it somewhat unique. It just adds a bit of excitement. I honestly don't care about how much something like that makes a card worth- I find more pleasure just owning it and knowing that THIS one is a little different.
Some people only care about the monetary part of it- and that would make collecting less fun to me if I had to concern myself with that. That is why I mainly just by a card and keep it.
But, there are so many ways to collect the T206 set and to each their own. I love everything about the set, the freaks, WST's, ghosts, crop marks, registration being off a bit- I like all that stuff. I also just like straight up nice looking fronts with a Piedmont 350 back- it's all fun to me.
One of the funnest ways I've found to collect the set- and to get that feeling of having something unique in my collection- is searching for (or finding by accident) tough front/back combinations. It is a great feeling (to me) knowing I have a card that maybe only a few other people have (because of the combination), and it doesn't cost thousands to do it.
This card is one of my favorites, picked up on the B/S/T from another board member (thanks again!) and as soon as I saw it I had to have it. It's huge borders add a uniqueness to it, it was affordable, and I have yet to see another. And no, I am not selling it

But I love knowing I have it- I think many people like having things in their collection that slightly set it off from another collection.
And, some collectors only want the cards that are so unique (hey Johnny V.

) that their whole set is unique in itself. Different strokes for different folks.
I can go on and on about this

Just adding my perspective.
Sincerely, Clayton