Main point there, is that there could be a possible way to break Lore in XIV and improve the Egis. Then again, SE would have to do something that the fan-base wouldn't be outraged over, and balance issues need to be heavily considered then as well, especially when we will most likely get Leviathan in some shape or another a month or few months from now, maybe not right at the release of 2.2, but sometime before August I'd warrant. You then have to ask, what do the other classes get from this? What do they get out of beating Leviathan if it comes to that?
XI is still giving us options to new Avatars, a certain feline is becoming available this March, then you had the 6 base summons and Carbuncle, Fenrir, Odin and Alexander in Treasures of Aht Uhrgan, and possibly even more down the road. How is XIV's Egis going to compete with the sheer amount of options that we had and still do have in XI? And how could they balance it out if we have access to 5+ different summons? I'm basing a lot on how XI was developed and programmed, but this points out a significant issue to me personally. If XI had access to 12(forgot Diabolos) summons in one shape or another, how could that be incorporated properly into XIV without breaking anything? And if SMN gets so many additions, what will be given to other classes to make them more appealing themselves? The fact of the matter is that SMN has an abundance of creatures to call forth from the wellspring that is Final Fantasy, what makes other classes more interesting if you have such great diversity added?