I wouldn't say "most people" install it, but I'd say at least 30% or more do. Certainly a large portion of the membership of this BBS. Most who don't install it probably think it's too risk or too much work. Neither of which is true. Some probably just don't think the features are important enough.

You don't lose any features. A new menu becomes available when you hold down the front panel knob with all the kernel features (max temperature warning, screen blanker, etc.)