[kh_hk]

You will start caring the day you want to update to Bootstrap 9000 and need to change the class names of all the properties that have changed. A counterargument could be that one could stick with the version already deployed, and that's fine too I guess.

For me it's about being in control of the situation. I will find myself changing things just for them to look as they are supposed to look like, and soon realizing that is not CSS anymore, just another framework being in between and making the work sometimes easier and sometimes harder. Using LESS at least gives you a bit more of control on the hidden spots, and opens room for sane customization.

I do personally prefer to not use a CSS framework at all, but if Bootstrap is a requisite on a project, using LESS is a no brainer.

[dsego]

Bootstrap already depends on the markup structure, which makes your point moot.

[kh_hk]

I do not really get your point, care to elaborate? Unless you mean that 'div' is subject to change over time…

[dsego]

A span2 div needs to reside in a row or row-fluid div for it to make sense. You can create your own classes that inherit from these, but you still need to nest them. Which means you can't change the structure of the markup willy-nilly. Thus, not using boostrap classes won't get you far.