I got a Vita recently for the first time, and I have enjoyed it quite a bit. But the memory storage situation is the worst thing about it. The PS Vita 1000 comes with no internal memory. The Vita 2000 (aka Slim) only has 1 GB included. Proprietary memory cards only go up to 64 GB, and that amount was exclusive to Japan.

I know there were other issues with the Vita, like the decline in demand for dedicated handheld platforms. But I think the memory card situation hurt sales of the hardware itself and thus support from Sony and third-parties.

The PlayStation Vita sales stand at 16.21 million units. But let's imagine this situation.

The Vita models launch at the same price. But there are no proprietary memory cards required. Standard SD cards are supported instead. The 1000 contains 2 GB of internal memory. The 2000 and PS TV contain 8 GB of internal memory.

I genuinely think this would do enough to make the Vita more affordable and more appealing. Do you think this would increase Vita sales, and maybe even syphon some 3DS sales?

I think the Vita could've sold around 32 million or so, matching or slightly passing the N64.

Slightly better, but considering how hard that gen got hit by mobile phones, I don't see it making that big of a difference. Maybe it could've been something similar to the PSP where many buy it as a homebrew platform, but that only goes so far.

PS Vita's performance has nothing to do with its memory cards

The weak point for vita is the lack of a killer app.

Sony really believes without the killer app and proper  Sony support, Vita will sell well( multimedia components, maybe cool design).

Sony takes the good move and focuses on Ps4, but vita clash against a regular Nintendo handheld with killer app e good support ( it's the worst Nintendo handheld, but has of good support by Nintendo).

Even on 3ds Nintendo always treat our handheld public like premium customers, otherwise, Vita, when ps4 launches, seems a PS4 addon. 

About the same. Sony abandoned the system after 1 year of launch.

Why do people always associate the Vita's poor sales to the memory cards? It was the lack of advertising, interest, and games on the system.

Pretty much the same, as it had more to do with Sony abandoning the playform than it did memory cards. The cards was just the cherry on top.

Exactly. If we list all the reasons why it failed from the most impact to the least, the memory cards will be at or near the bottom. 

The biggest problem with the Vita is obvious. It wasn't a hybrid console.

It was a mobile + handheld console Hybrid. Then they made a Home console version which failed for obvious reasons lol.