It seems that every UFC event which passes without a submission win results in some idiot somewhere (blog/forum/facebook) stating that jiu-jitsu is useless in MMA now, or the guard doesn't work in MMA anymore. I think that is total nonsense; for a start there have been many UFC events with a high number of submission wins plus every fighter still needs to have high level grappling skills to be able to compete at the top level. There is also the simple fact that nearly all UFC champions current or historic have had high level BJJ (with a huge number of them holding black belts). That obviously doesn't mean they all use jiu-jitsu as their main attack (Anderson Silva) but they have the skills if necessary (Silva/Sonnen).
Anyway, I do think there are a lot of problems for jiu-jitsu in current day MMA, but they are all due to rules (or application of rules) and judging. Rules first...
Something that happens in nearly every fight, where one contestant is looking for a takedown near the fence, is grabbing the fence to prevent the takedown. There is no other foul I know of which fighters can commit so often without any penalty. I have seen fights with multiple grabs every round, and each time the ref says "If you grab the fence again I'll deduct a point" but they only very, very rarely do. I don't understand this at all... grabbing the fence is a choice, it's not possible to do it accidentally and it can easily change the result of a fight (if the takedown landed it could result in a stoppage or sub). As it's something which must be a purposeful choice of the fighter, I think it should be an immediate point deduction. People argue that it's a natural reaction but fighters should train so it's not.
Probably a bigger problem for jiu-jitsu in MMA is fights being stood up. Preventing fighters from not attempting to fight is a good idea and there is a rule to cover this as "timidity" is a foul. I think it would be much better to utilise this rule rather than rewarding a fighter by standing them up. At the moment, if a fighter gets taken down by a much better grappler they have no incentive to try to fight as it's a much better option for them to just hold on and wait to be stood up. So why is the choice to avoid fighting (i.e. timidity) being rewarded rather than penalised as a foul? The equivalent would be for an inferior striker to just constantly back-pedal and run away (Kalib Starnes vs. Nate Quarry... but I don't think Starnes even got penalised?) which nobody would consider ok, yet for some reason everyone puts up with a refusal to engage on the ground. If you don't want to fight on the ground you should have to prevent the takedown or fight to stand back up again.
The rest of the issues are judging/scoring...
It's been shown time and time again that judges will not score a round in favour of the fighter on the bottom pretty much no matter what happens. Considering that fights are regularly won with submissions from the bottom I find this crazy. If a fighter gets a takedown then spends the rest of the round defending sweeps/submissions while landing ineffective ground and pound to the body, they should lose the round. The argument is that they are successfully defending, but again the standing version of this would be someone avoiding all the strikes thrown by their opponent and winning the round for it.
Another issue is how do you score grappling compared to striking? A strike which lands with 90% effectiveness could knock someone out, but a submission attack which is 90% successful can result in no damage or positional improvement at all. But surely consideration has to be given to the fact that the fighter almost finished their opponent? It's a tough to balance the two areas but I think judges need to start scoring sweep and submission attempts higher.
The biggest problem with the judging of grappling is that people who haven't done it don't understand it. Even people who haven't done any striking can easily understand that hitting some more and harder is better (although even with striking there have been the problems of judges hugely underestimating the power of leg kicks) but when it comes to grappling it is almost impossible for someone who hasn't done it to understand what is going on. There could be an almost submission and some judges may not even realise and it can be even harder to tell who has the advantage in a guard position. I really think that MMA commissions should start to employ judges who have fighting experience, preferably in both striking and grappling.
Whether these things will ever be changed I don't know, but I do think they would all help to balance the power of striking vs. grappling within MMA contests. Using jiu-jitsu in MMA is definitely harder now than it used to be, because the overall level of knowledge is now much higher, people have learnt to wall walk and get back to their feet and lots of fighters only try to defend and land ground and pound, so leaving far fewer openings for attacks. I think some jiu-jitsu based fighters need to use more strikes on the ground too; often you see a fighter lock on a submission only to not finish it and they could have landed strikes while in the position.
One thing is for sure, jiu-jitsu in MMA will never die (the sport would no longer be MMA) and any article which suggests otherwise is worthless.