If you had a store where 10 people were playing Standard and you release a bunch of Commander product and 6 new people come and start playing Commander, its not surprising that some of the Standard players might make friends with the Commander players and want to play Commander with them, and that can shrink the Standard audience
Kaalia is has been among MTGs best commander decks for a long time because cheating mana costs is almost always broken, so with Kaalia you want the biggest, baddest creatures of the types you can find, like Avacyn, Angel of Hope or Vilis, Broker of Blood
Caesar hits so many favorites for me: hes inexpensive, hes got a decent power and toughness, and with a little sacrifice, he becomes a problem quickly while doing everything that Soldiers wants to do, make more Soldiers and deal damage
Whenever you cast an Instant or a Sorcery, you get to create a 2/2 Blue Drake with flying