Can i have my rp transfered from my banned account to my new acc?

No. I wouldn't assume so because you forfeited all purchases in that account upon being banned.

I've never understood how people who are spending money on an account don't take better precautions to not lose that account.

sorry dude, but no. thats actually the main incentive to avoid being perma banned. on a side note though, you can always create a smurf account that you will never play with, then only add RP to that account. from there you can simply gift any of your other accounts or your main.

ofc this wont stop you from losing what you actually bought, but at the very least you wont lose all of your available RP funds. thats what i do anyway. im 99% sure im never going to be banned considering im not a general douche to my teammates, but i do like to play things like this safe

There would be no point to perma ban if that's the case

The point of a permaban is to tell you "you aren't welcome in league".

Riot doesn't want to make it any easier for people whom are permaban ed to come back