It is true that if you cut all of your pieces with a 1/2" seam allowance and sew a true 1/2" seam, your blocks will be consistent. But as MadQuilter said, some blocks have bulky seam lines with a 1/4" seam and it would be way more difficult to get them to lay flat with the extra 1/4". Now, having said that, I suppose you could trim back the seam lines in those areas after they are sewn and then press them. Some patterns, having a wider seam allowance, even pressed open will show, and it could spoil the look of the block...that 1/2" shadow, 1/4" is not nearly as noticeable.
I usually press to the side, but there are exceptions to every rule, too LMBO On some blocks it is just easier to press a seam open when you have many seams ending in one location, like Kaleidoscopes and such.
But it does boil down to this, it is your quilt!!! If this makes you feel more comfortable, your blocks come out consistent, and you are a happy quilter...then carry on!!! :D:D:D