i somehow never noticed this before... but 3DS isn't getting enough releases on a regular basis

Not really. Generally software sales drops lag far behind hardware drops because a lot of people don't upgrade their consoles right away and need to do SOMETHING.

That's why PS2 got releases so late in life.

e-shop

What is so strange about a console that has 1/2 the user base of PS360 is selling 1/2 of the games on a weekly basis?

Seems pretty logical to me.

Handhelds have a high rate of digital sales. I know the Vita does, and I assume the same is true of the 3DS. We know for a fact that the Vita sells a lot of copies via PSN, with some cases in Japan totaling a hefty percentage.

I don't think retail numbers should be compared with the same scale across handheld and home consoles.

As Superchunk said, it's exactly as it should be.

pretty much this

I would say that the "attach rate" isn't great, especially considering it's been on the market for two years now, but two things to consider:

A) Handheld's tend to have a lower software 'attach rate' than consoles and

B) Digital sales are picking up so much steam (and aren't tracked - or trackable, really, that I know of), that the software numbers are certainly misleading in that regard. Between the VC and 3DS eShop, I have no doubt that the 3DS is shifting decent volumes of software each week. Same likely can be applied to Vita.

No.
And that's all that needs to be sad.

Its because of the eShop, full digital games spike during the first quarter of the year. Fire Emblem Awakening surpass the retail version in sales. This is why Capcom is releasing the latest Phoenix Wright game is only going to be digital because they can save money on not making a retail model and notice the spike in digital sales. The eShop became quite a success for Nintendo, I hope the Wii U eShop gain that success soon.