You know, I wanted to write an article on that very question for my site at one time, but I never got to it (like 40% of the things I've planned for the site...)
The truth is, I don't think Legends would work on Nickelodeon today, and it would be challenging to adapt it to today's kids. The way I see things, kids are exposed to much improved technology than the Legends era, and value realism a lot more than they used to. In addition, kids' imaginations are less-developed than they were 13 years ago. Considering both of those facts, the idea of a talking stone head would not "fly" with today's kids as well as it did before, not to mention the rather uninteresting history lesson he tells.
Now, about Kirk... both his criticism and compliments come from the fact that he remained relatively calm through the course of the show. That, combined with his largely unvaried speech, prevented him from cracking stupid jokes, or being too eccentric. He may not have been a favorite of the kids watching the show, but it didn't matter because that was Olmec's job. If they redid the show today, there's no doubt in my mind the network would hire a host like Jason Harris, with too much energy for his own good.
I can just picture a better-themed temple, though... Larger rooms, foliage everywhere, waterfalls... it could really be splendid if done right. Also, studio 18's ceiling was only 33 feet off the ground, which didn't allow for much vertical expansion. But if the ceiling was higher, spacious rooms would be awesome. I have a design I think would be great, but it's be tought to make a picture of.
Discovery Kids' vision with Endurance is exactly what it should be for Legends.
By the way, forgive any typos you read in this post. I had to type it quickly...