I'm sure you've seen or heard OBP, on on-base percentage.
Since this includes getting on base by walk or hit by pitch, those get added to hits for the numerator.
Plate Appearances, not at-bats, are used for the denominator.
So, Plate Appearances are actually used in the calculation of an important stat.
If they didn't, a guy who walked 90 times would see there OBP 150 points higher than the batting average. But, the 90 gets added to the denominator, too.
To whit:
Say a .300 hitter has 600 at-bats. 180 hits. Now, let's say that guy walked 90 times.
He reached base 270 times. With 600 at-bats, his OBP would be .450.
Instead, that 270 times reaching base is divided by (600 at-bats + 90 other plate appearances), or 690 PA. The OBP would be .391.
Now, having an OBP 30% higher than the average is really good, but it's not .450.
Rose walked about 1,560 times. That's 60 something per year, which is good, but not great.
That's why his batting average is tied for 137th all-time but his OBP is 240 something on the list.
He didn't get on base often enough to push his all-time OBP into the upper stratosphere.