for mma, it is advisable to have suffiecient standup to withstand the top strikers, enabling u to clinch, from there u can work takedowns. once u take them down, then u can work good positioning and look to pound or sub them. thats my take on it
however, one can argue that takedowns are pointless against guys that defend the takedown easily such as crocop. but if u have a look at his 2 recent losses to fedor and hunt, then it was a style vs style problem he had. fedor is too strong in the standup for crocop to ko, and crocop knows he doesnt want to be on his back, thats why he rode his bike all match.
also with hunt, crocop knew he would have trouble knocking him out, and he didnt want to trade with hunt, thats why he too was on his bike for that match.
when crocop lost to mino, he was giving nog the bash all match, and i think that a combination of fatigue (as nog finally got the takedown) and lack of knowledge led to the armbar
for general self defence, bjj is a good art to know. traditionally, it was taught as a means of self defence, and in a lot of the academies, the self defence component is taught regularly as part of the training. although a lot of it has evolved to the sport context of submission grappling. i mean, on the street, no one really wants to know how to set up a half guard sweep