Why were Goten and Trunk given less attention to Gohan with regards to their strength

[MasenkoHA]

In early DBZ a big deal was made of the fact that Gohan actually has a lot of hidden power when he’s angry and was far more powerful than his dad at that age.

But other than some shock at the two going Super Saiyan so young nobody really seemed to pay too much attention to the fact that Goten and Trunks were vastly more powerful than Gohan and Goku at the same age?

[Lionel]

The conditions encompassing their limelight made them see "less" by comparison to their elders. Goku, Vegeta and Gohan had attained new transformations -- two of them having committed to earnest everyday training under unique conditions. Goten and Trunks were never quite as serious as their fathers when it came to training. It doesn't help that the severity of the threat they were confronted with prompted them to use a power acquiring merging technique which overshadowed their individual strength. Next to that, when Gohan was born, Goku had settled down into a somewhat domesticated lifestyle. Although I have no doubt he continued with his training after the 23rd tournament, the gains he made were likely less on a percentile basis thanks to the family life he had plus his probable confidence in being the strongest on the entire planet. Gohan had the benefit of being conceived during this relatively peaceful period where Saiyan transformations didn't exist yet and the power attainment was relatively subdued.

All that being said, some statements made give the implication that Gohan has the greatest potential of any first generation hybrid on the show. Don't ask me why that is. Perhaps part of it stems from stronger maternal genetics in comparison to Trunks. Have you seen what Gohan's grandfather looks like? Such natural musculature and physiology must have a genetic component. With that said, it still doesn't explain why Goten's potential wouldn't be fathomless like Gohan's. My only guess is that the comparative health and youth of Gohan's parents when he was conceived played a role next to when Goten was conceived, which would have occurred as Goku and Chichi were entering their 30s. There are scientific studies and observations to indicate that aged parents who conceive have a greater chance to give birth to children with greater possibility for defects. Admittedly, 29-30 is hardly "old" for childbearing. It's just that when Gohan was conceived, both of his parents could be argued to have reached the zenith of their fertility (20-25). By Dragon Ball terms, could that have some role in the development of Gohan's power?

[ulisa]

A popular theory I’ve heard thrown around which actually makes some sense to me is:

Half Saiyans without tails start with a huge burst of power then taper off as they age.
Half Saiyans with tails take longer to gain power but can pursue it longer.

Whether there is any truth to that is up to opinion. It could be a simple matter of luck of the draw. Maybe Trunks and Goten, while inheriting Saiyan blood, did not have it on the same level as Gohan.

I’ve also heard the idea that Gohan has the most potential of the mixed breeds and it makes sense to me. Ultimately, I’d like to think that because Gohan was exposed to more battles than Trunks and Goten that his power had a chance to grow with more variety.

There’s also the point of that the audience grew up with Gohan. So there’s more interest in his power. The fact that Goten and Trunks transform like it was nothing also kind of removes some of the wonder of it.

[TobyS]

In my head I think that although they have “potential” they will never have the mad experiences Gohan got alongside the real Dragon Team, so they will never become seasoned warriors.

Now super has become the “Goku show featuring Vegeta” the rare occasion they feature other characters doesn't give them enough time to also develop Goten and Trunks to be worthwhile characters. Whereas a five second badly animated showing of say Piccolo or Tenshinhan sorta “works” straight off the bat because we at least already know who those guys are and what they are about from back when DB was consistently good.

[Lord Beerus]

Toriyama didn't have anything planned for them until he introduced the concept of the Fusion Dance, and it was only then the power they possessed at their young age was treated as the biggest deal in the universe.