The "NGP" doesn't nullify games and it's not digital only.
What's the non-digital then?
Limited space? I store my psp games on my PS3 (250gb) and PC (several Tb) for quick and easy file transfers. The psp Go has 16gb built in and I added another 16gb card. I currently have 17 psp games, 6 ps1 games, and 2 demos on my Go, with over 10gb free for more content. I'm not saying it couldn't get filled up but as long as I don't erase my save files I can erase games and swap as I like. If I plan ahead I could have enough games without carrying any umd's to last longer than any vacation has the right to last.
The only argument against digital that matters to me are:
1) Prices stay higher for longer than physical copies. It forces me to have greater patience while waiting for sales.
2) If you are into reselling games, which I am not, it effectively kills that off.
I do have some UMD games that aren't even available in digital form which is slightly irksome. Even if I were willing to repurchase them I currently couldn't. Namely FFI, FFII, FFT War of the Lions, and Castlevania: The Dracula X Chronicles. We'll see what happens. I hear FFI and FFII are coming to PSN soon. Tactic Ogre remake is coming to PSN and Third Birthday seems to still be in the air. Overall I am satisfied. If I want to play those UMD titles I can still play them on my PSP2000.
Believe it or not, that's not for me

I hate moving stuff from one medium to another. I prefer to keep certain things on one medium and the only reason it's on another HD or Disk or whatnot is to back it up. Which means, for me, with the amount of games I'd end up having for it, it better have enough space for ALL of them. It's kinda an OCD thing of mine, but so be it.
Do you only have an ancient computer with a whopping 5GB of storage space? Most PSP games are the size of a CD(~750MB), some of the bigger, newer games are 2 CD's (~1.5GB). That's not big at all. You can buy a 16GB MSPD for about $50, which will hold at least ten games for you to just carry around, not including the ones that can sit on your hard drive if you don't want to play them right now. They're taking up very small amounts of space in today's computing world. UMD's are dead, get over it already.
If you don't want to buy them, just download them, you already have a legitimate copy of the game, so you're not stealing in any sense. Legally, you are obtaining a backup of your purchased product, it's why ROM's are legal; so do that for the games you can/will not legitimately buy a digital copy of.
Honestly, I wouldn't buy the NGP if they were still going to mainly rely on proprietary physical media; period. Digital Downloads make infinitely more sense for a portable hand held, where there's no way I'm going to be walking around with 10 jewel cases in my pockets to hold the games I feel like playing today. Do you listen to 8-tracks in your car too?
See above, I don't like the idea of digital downloads unless it has enough space to store ALL my games. And, believe it or not, I do have more than 10 games for the PSP and I'd likely have those + the ones for NGP. I don't care to rebuy the UMDs into digital format (which I'd have to) and I'm damn sure they won't release a legal option to change the UMDs into digital. So even if there was enough space, I'd have to carry my PSP if I wanted to play older PSP games. And,yes, there are still some I enjoy playing.
So the only reason I'll get an NGP is if there's 1) enough space for ALL my games and 2) if they offer a solution that doesn't make me pay more for making my UMDs become a digital format. Until I know more about the NGP, it's unappealing for me to get yet.
And I've never had a problem carrying the UMDs around with me. I don't keep them in the case, I have them in a special storage thing my art friend made for me to hold em but hold many of them at once. And I keep it in my bag. It's worked out fine and I haven't minded the UMDs. Still, I agree, it would be nice if it was all digital, but that would mean it'd have to have enough to hold like 50 games >.> sure that's a lot, but I'm like that.
Like, with my computer, I have old games I haven't played in a long time and not into yet, but I leave them installed (and if I ever reformat my computer I reinstall them all) in case I want to and whatnot. My nearly 2 TB of HD are filled with like 500 gigs of games, 200 gigs of work programs (things I use for school or job) and then the rest are downloads (I never delete downloads too

). I'm weird like that >.>