The Energon Pub

I heard in one of TFWire's reviews that all Transformer toys are preceded either with an "autobot" or "decepticon" as in "Autobot Jazz" and "Decepticon Megatron". Any Can anybody explain this to me? How could Hasbro lose the rights to using names of toys they carried for years?

Not all but some. Megatron and Optimus Prime for example they've kept in pretty much constant usage, others like Jazz have been allowed to slip when there wasn't a toy bearing that name for a while. If there's something with a similar name under copyright when they want to reuse a name or if it's a name that's too generic to get a firm copyright on they can get around this by using the prefix, hence Autobot Jazz or Decepticon Brawl. To begin with Hasbro didn't reuse names as much as they do today and it probably wasn't expected at the beginning that the brand would still be going strong 20+ years later so over time some copyrights have been allowed to slip. Just the nature of the beast.

Some, like Trailbreaker and Motormaster, have been trademarked by other companies. Hasbro will often have to be creative when making homages to these figures.

A trademark isn't indefinate. As said before, if allowed to slip and not reissued, another company can trademark the name and you lose it.
It's not like the 80s anymore where copywrite laws and trademarks weren't nearly enforced as much as they are now. Back then you could release Bumblebee as a VW bug without permission, now, they'll sue.