So, you have 35 bottles of wine. Let's just say the average price is $12/bottle. That's $420 of wine that you know will not hold up as well or be as good as if it were in a cooler. Furthermore, that cooler will protect your current wine and future wines. All in all it's a pretty simple argument.
I have four wines (12 bottles) that should mature from 2009 - 2012...This 28-bottle cooler won't be enough for me at some point. May have to buy a second one...
With regards to the 1/2 bottle thing...I've heard a lot of people say that taking a bottle and corking it and putting it in the fridge does a great job of preserving it...I put my 1/2 bottle in the fridge two nights ago and will drink it tomorrow night...Should be interesting.
Another tip that I read was to take marbles and add them to the bottle until the wine is at the top and then cork it as you would have the 1/2 bottle. The big benefit to that, in my mind, is that I usually would never drink exactly half (less than half if you do the math) of a bottle...So the marble trick is probably a good one. For now I'm going to continue to use the fridge until I have bad results and then may get some marbles.