It likely doesn't mean anything at all and some characters just have specific dialogue depending on whom they fight, so they speak in a specific order.

Kotal replies to Raiden, afterall.

Nope, don't find it strange. I actually think this shows more creativeness when it comes to interactions.

Kotal was probably the first player even though Raiden was on the left side.

It probably was the less revealing interaction or the only one they came up with so far, I'm sure normally the P1 would go first since it seems like they'll make two interactions for each pair of characters depending on who goes first.

At least that's what I'd hope, there'd be more dialogue content that way.

So far, at least for E3. The vast majority of batitles had two distinct interactions based on which one of the two opponents was P1.

Lol i wonder what they are planning on doing when it is raiden vs raiden

Lol subby vs subby:

-"You are not the true Sub-zero"
-"Imposter!"
-"I will return you to the Sea- (of Sub-Zeros)"

Don't read too much into it. I personally think it doesn't mean anything.

If you noticed in the Sub Zero vs Scorpion fight. Scorpion was on the Left Side (P1) and Sub Zero was on the the Right Side (P2)

and I quote
Subby- Shirya Ryu Dog
Scorp- Lin Kuei Scum
Subby- Death is more honor than you dersever

https://www.youtube.com/watch?v=ejTIvrjmXw8

I really, REALLY hope they have more intro's together and not just 1 stupid one.

scorp and subby have two tho. But your right, I shouldnt read too far into it because its still so early and there's no way they have finished even a quarter of them yet.

I'm one who can care less about dialogue. I only watched all the characters intros once in MK9 just to see how they appeared into the match. Same will be done with MKX. If there is dialogue here and there throughout the fight, then that will do as we won't be able to surpass it.

We did hear Kotal Kahn speaking quite a bit during the match. Since he probably has had more time to be worked on his in game dialogue was added. It will be interesting to see if the characters interact during the fight, That might be kinda cool. If not, we may just see certain moves for certain characters having dialogue.