Not sure if you meant to ask me this specifically (you quoted me just before this so I assume so) as I actually do raise them for meat and eggs, but it's a secondary benefit to raising them to improve the project birds. Other secondary benefits include controlling ticks, consuming bugs, producing manure, and yes, enjoyment.
If you want meat and eggs, I figure you may as well actively try to improve your flock when the side effect of your efforts will be meat and eggs anyway. I don't want to hatch every egg (poor color, size, etc) and I don't want to breed every bird (health issues, poor conformation to standards, bad attitude, etc). But to get a good selection I need to raise lots of birds, which means I will either have to eat them, sell them, or be buried under a pile of eggs.
And this is also why, back to the topic, I will sell eggs that would be more valuable as hatching eggs (even with poor quality) as cheap table eggs. I cook with them too, you can bet that frozen custard I made with 12 Silkied Ameraucana Project eggs would have been expensive indeed by hatching egg prices. That was also one expensive crockpot chicken the dog ate as a treat on her food last week, going by the price if I had sold the rooster as a live bird for project purposes. But...
I don't want those eggs to be hatched, or those birds bred from, as they would produce substandard birds that would not contribute positively to the project and would not enhance anyone's flock. That's why it's actually worth the loss of potential profit to sell them as table eggs or eat them for dinner. So in essence it's not that them being hatching eggs makes them somehow more valuable, it's that the table eggs are less valuable because of the reasons they were disqualified from being hatching eggs for.