Thanks for all the (mostly) civil replies in this thread! I knew that several folks wouldn't agree with me but thanks to those who did it respectfully. You all make good points.
So far, after reading the responses, I'd have to say that this is the best argument I've seen for buying a yearly subscription:
I will say that because of my DDI subscription, I don't feel the need to buy any book which contains only lists of powers, items, races, monsters, classes, etc. So I won't be buying AV2, Arcane Power, Divine Power, Monster Manual 2, PHB2, etc, because the DDI compendium is as good a way, if not better, to reference that material. My 60 a year gets me ~100 bucks worth of material, before any of the extra stuff.
Personally, I still like having the books in my hand, mostly due to convenience - I play with several people who do not own and will not ever get an online subscription, so it's nice to have the physical books to pass around and look at things. Plus, they are often organized in a way that is slightly more useful than online materials - most of the time.

However, this is a good point: that buying a $60 subscription gets access to a $100+ worth of books. But, it still doesn't convince me that waiting until the end of March wouldn't be a better idea: by then, we may have seen enough content released to make that equation work.
My main issue with DDI right now is that while access is nice, there are a ton of 3rd party solutions that already exist that are better than some of the DDI services. And until these 3rd party solutions seriously start to fall behind - my guess would be that one or two more content books will start to sink many of them - there is just no reason to pay for something you can get for free, especially since the free product can be just as good (or arguably better, considering it's... well, free).
In particular, after many years of PC gaming and getting more and more jaded with the state of the industry (combined with the general lack of editing quality many of the D&D books have suffered from for the last few years), I have gotten extremely tired of paying for
beta products. It's bad enough that I have to pay for a book that no one read before sending to the printers, but to be asked to pay for a beta product for character creation just pushes me past my limit. Don't get me wrong: I really like the character builder, and I have high hopes that one day it will be a finished software product. However, today it is not. It is a beta product in gussied-up wrapping paper. In fact, there are arguably more bugs in this version than the beta.
I sincerely hope that all the people who paid to effectively be beta testers of this product will help shape it into something that will be truly amazing. The potential is certainly there. However, it's worth waiting - at least two more months - before putting your own money down and paying to help them beta test it a little more. Hopefully soon we'll be graced with a finished product. Two months from now, I am sure it will be better.
As for the other qualities of DDI, I mostly see access to "insider" or "preview" information as something without value; I don't want to pay $5/mo just so I can see what a druid -might- be like 3 months from now: I am happy to wait 3 months and just get the finished (HA!) book. It's like paying for exclusive access to video game content that gets released for free in a month: why would you do that?
The encounter builder is still the lead runner (the ability score generator being the easily most worthless of all DDI offerings) for something you might find real value in, but even that by itself is not worth the price, especially since 4.0 has done an AMAZING job of making one of the hardest parts of 3.5 - encounter building - so easy! (Sadly it also made one of the easiest jobs of 3.5 - treasure distribution -
incredibly hard, but maybe one day we'll get a loot builder flash program as well. That would be worth nearly $5/mo right there.) Dungeon/Dragon are things that again, if you follow the magazine and were already a subscriber, then you're recovering a good bit of cost. But very few magazines are worth $60/year, and these two are not in that short list (especially since they, too, are often filled with "preview" content). Even getting two magazines together along with the encounter builder is still not worth $60/year.
Again, I'm not arguing that this content has no value. And I am not arguing that it will not be great. But I am saying that rewarding a company - any company - with your hard-earned dollars for releasing incomplete products is a bad idea. It is up to us, the consumers, to use discretion in our purchases so that companies understand that we are not willing to put up with beta products released as finished products. Do not reward WotC for giving us a beta character builder instead of a finished piece of software: wait. Wait, make them work a little more to complete it, and then give them money. We will all be better off in the long run if you do.