The problem people have with normalizing...
...is not so much in the actual normalization (which as Tom mentioned, simply increases the overall signal level by a factor), but that if you have established the appropriate level balances from song to song on a cd, using normalization will absolutely kill those balances.
For example, if track 1 is a hard-rockin' tune, and track 2 is a ballad. It's a given that track 2's overall level should be lower than that of track 1 (since, in real life, when will a ballad be as loud as a full-out, hard hitting tune!?!?!). If you normalize track 1 and track 2 separately, that carefully balanced level relationship will be destroyed, resulting in an unnatural-sounding CD!
Bruce