I just bold mine because I find it easier to reread my post (I tend to reread before making a post so I can make sure someone is responding). My eyes are also pretty bad along with the limitation of having to read via iPhone screen. 

It's is still better to just explain and read the actions, I just feel bolder speech is like a little sugar for those who have a harder time. Especially those who need to catch up on reading because they leap in the middle of a rp. 

But I don't mind those who don't use colors or don't bold and italics.

I used colors on the old guild, usually bright visible ones. But bold works as well.