Any VC that asks you to vest your shares is a VC who is trying to steal from you.
The business pre-money valuation is value you created. Your ownership of that is property you have EARNED.
When you take VC money, they get a percentage of the company, and your ownership is diluted, but at the same time the value of the company goes up, as it now has more cash assets in the bank. The end result is immediately post money the value of your shares should be about the same as pre-money, only the ownership percentage of the company is less.
This is fair, and this is the consideration you give up in exchange for their investment.
However, if they ask you to also re-vest your shares, are asking you to give up you property (and your voting power) in the hope that you will "Earn them back"... which first assumes you hav eto earn them (eg: it is a losss of property if you don't own it anymore) and secondly assumes that they won't have pushed you out. While your shares are vesting you can't vote them, which gives the VC even more power.
Finally, they are not giving you consideration for these shares you're putting in jeapardy and so they are simply asking you to give them something for nothing. The investment they are making is already paid for by you in the dilution you are experiencing.
There is absolutely no reason for a founders shares to re-vest.
If your ownership in the company is not enough to ensure your interests are aligned with the VCs (Who really can't do much to make the company do well, but you can.) then the VCs wouldn't be investing-- period. So the alignment of ownership excuse is patently absurd.
No reputable VC will ask you to vest your shares. Only a thief would do that-- you own the shares, and asking you to give them up for nothing is trying to take advantage.
If a VC wants to put you on a vesting schedule to keep you incentivized.... let him offer you shares out of his pool to vest into.
Anything else is exceedingly greedy on the part of the VC.