Why pitch doesnt go round numbers? 124,99 - 125,03...

All to do with percentages and the accuracy of the pitch slider at the selected range. Sorry!

Are the people dancing complaining that it's 125.03 and not 125.00? ;)

Obviusly is not becouse the people is listening a song faster or slower is another thing.
If your playing tracks at 125 for ex, and then load the next track which is coming with 126, you try to adjust the pitch manually to 125, then it wont match for .03 it will disadjust later on, in 30 seconds or 1 minut it will sound bad!, you need to be paying attenting to one thing more, and it should not be like that. 
So if you want to avoid that mistake, becouse your sesion is quite load with effects and you want to do cool tricks,you will just use autosync, like noobs does with Hercules DJ console, and one problem less. But this is not promoting to mix properly then.
Or maybe i dont know how it should, im not experience DJ i know.

Do experienced carpenters use a manual hammer and nails, or a hand saw when building a house? No. They use nailguns and power saws. Why? Because technology has provided them with options to get the job done quicker than the traditional methods.

There are plenty of experienced DJs who know that using the sync feature of a hardware or software DJ solution isn't cheating; they use that tool to beatmatch for them so they can focus on other things, like picking tracks, using effects, entertaining the crowd.

It's not about mixing or NOT mixing properly when using these available advancements in technology -- because if it is, I'll start down the rabbit hole of "why aren't you using vinyl"?