Personally, I believe grappling is fantastic for MOST fighting situations, but it is not the end all be all. For example, if I was approached by multiple attackers, a single leg takedown, to a side mount, to an arm bar isn't an option. The multiple attacker is dangerous to any ground fighting situation. Striking and Joint manipulation are two excellent tools for multiple attackers, as well as some standing submission. A one on one fighting situation allows the person to use grappling more freely and incorporate striking and joint locking as well.
Weapons are a different story.
My advice is always offer anything the attacker wants until you feel threatened or they want to take you with them. Then I say, fight for you life using any and all techniques that come into mind. I believe that grappling can be taught to all ages. I do think that what should be taught be limited. Takedowns and ground positions should be taught at all ages.