I don't know if it's a real need or if I'm the only one interested in this possibility ...
I use pChart to show value corresponding to an average number of things by hours. For example, beetween 8:00 and 9:00 I have 4 things, beetween 9:00 and 10:00 6 etc.
If the value 4 is on the tick 9:00 and the value 6 on the tick 10:00, user thinks that these events happen at xx:00 and doesn't understand that these value are average data by hours.
I don't know if it's very clear ... Ask me if you want more detail ;-) I've patched my installation to generate graphes with a half-tick gap beetween value and abscise ticks/vertical lines (see attached picture)