Why not just release the originals in the cinema again, hell they would make more money doing that then releasing a remake.
That is extremely questionable. Profit percentage-wise, yes they would make more. But, if you were to take The Omega Man and rerun it, then you could see
maybe a million or two. But even with I Am Legend's high budget, it made a freak-ton of money.
Hell, take a look the Dawn of the Dead. You could rerelease the original and make a little more. The remake took in $102mil worldwide on a $26mil budget. You can't put up those numbers with a rerun.
Oh hell, here are some more remake totals:
Texas Chainsaw Massacre:
Budget - $9.5mil Gross - $107mil
The Omen:
Budget - $25mil Gross - $119mil
When a Stranger Calls:
Budget - $15mil Gross - $66mil
The Amityville Horror:
Budget - $19mil Gross - $108mil