Tell me why everyone wants DinoBots in TF3?

I thought the plotline for the movie was great, I would have prefered to have them name megatron to galvatron so we could confirm unicron, but in any case I don't think that Grimlock would destroy the storyline or be too silly, seeing as Bay is all for the jokes when it comes to his robots (i.e. Devastator, Wheelie, The Twins, etc). So if anything matters, it's how many kids buy grimlock's toy and yell out "ME GRIMLOCK!" at the end of the movie.

Then they wouldn't be Dinobots would they?

The idea of the Dinobots as robotic dinosaurs with vehicles altmodes sounds awkward to me - I don't think their robot modes are any less important/iconic than their dinosaur modes, to the point that they have to be left out entirely. And don't even let me get started on the overly complicated 'Dinobots as triple changers' idea. Robots with dinosaur altmodes are good enough for me - given the rebellious nature of the Dinobots, it would only be in-character for them to snub their noses at the concept of disguise.

There may be no peace for the wicked, but the righteous can damn well get a piece whenever they feel like it.

Agreed.

Only if Grimlock gets his retarded animated personality.

Without Animated Dino's sissyness.

To be fair, their cybertronian forms were tanks and other military stuff. At least WW Grimlock was some sort of huge tank.

Honestly, I could see some really sharp stories coming out of Organic altmodes. With a race that is now doomed as they will all run out of energon now, who is to say some Tfs in the universe have not adapted and found new ways to survive and sustain themselves?

Hence "Beast Modes" where they can adapt Tf bodies to integrate with Animal DNA to give Tfs the benefit of 'living tissue' to protect them and generate energy for them.

So Wheeljack and an almost dead Grimlock show up to earth with this Technology but the issue is they need Animal species 'large' enough to support full-sized Cybertronian species. Hence where Dinosaur Fossils come in. They take the DNA of Extinct Dinosaurs which are a large enough to species to support a Cybertrian frame.

And of course some advanced plot goes by as this is a secondary plot and Megatron and Prime are fighting over some Macguffin and Megatron corners Prime and says "Who will save you now?" and out of the background a Trex stomps onto the scene and roars and tackles megatron, and after a horribly extended spinny scene he transforms into Grimlock and says "me grimlock always have to save Prime's bacon" or some other cornball line.

There you go... Hell, Wheeljack can even convert Wheelie into Rattrap as an experiment earlier in the movie.

All it needs is some sort of Macguffan or a plan by megatron to destroy earth and they can begin filming on this bad boy.

The network will feature content from Hasbro's rich portfolio of entertainment and educational properties, and content from Discovery's extensive library of award-winning children's educational programming, as well as programming from third-party producers. There will be no "Transformers: Buckets of Blood".

Uh, they are Transformers and much loved by fans. What more do you need? Its the only reason any of them have been in the films. They don't necessarily need a story built around them or serve any purpose.
Since you mention it, the Dinobots were used most of the time to take on Devastator.
As for their alt modes, its not so hard to come with 'why'.

This Devastator is a little different than G1 Devastator. And yes there Alt modes aren't as easy to explain as the G1 Dinobots alt modes as they were built on Earth in the first place.

I'm not completely against them, I just think there's no way to have all 5 Dinobots be in TF3.

You said WW. Shhhhhhhhhhh. They never had Cybertronian forms as they were created on Earth by Wheeljack and Ratchet.