To Be Honest, dont feel like you missed out, its more a thing of them getting the time to build the games for ease of use.
Underworlds as a 2 Player In BOX strat board game is great and Kill team is way way way more of that and closer to the normal game of 40K
I only got into painting and some Underworlds, now in Dec my wife got the Kill Team Starter set, and we have played the 3 into games, now onto the last and now she is also into the start of the different teams. The thing about Kill Team for me is that you can buy the box with the full team in one shot and play from there! no extra needed.
Wish there was meetups one could join. There is alwys time. I find Kill Team to be the best into to 40K series! and much cheaper then having to want to but a full 40K army