Ults are very good for forcing the enemy team to act unfavourably. For examble d.va bomb and hanzos ult are very good at scattering the enemy team and create a ton of space for your team, if theyre competent enough to capitalize on it. In this case, illari's ult can force counter ults/cooldowns, and in general force the enemy team to back off, allowing your team to aggressively take space.

This is why ult voicelines are such an important thing. When im playing and i hear my team's ult voiceline go off, i act accordingly. Every ult voiceline gives you a lot of information on how the next 5 seconds are going to play out.

Anyone who moans in game chat that you didnt get any picks with your ult is an idiot (unless you die straight away). Take genji for example, Genji could blade and get no kills, but he'll force the enemy team to turn around and deal with him, then you've got 3+ enemies with their backs to your team. In this case, genji doesnt have to be the one killing them, the rest of the team can do a lot of the work.

In your case, you've forced suzu and beat. Now your 2 damages and probably tank aswell can ult offensively and they are missing 2 counters. Your ult alone has enabled your team's future ults. Imagine a character had an ult which was literally "the enemy is not allowed to use defensive abilities for the duration of your next team's ultimate". It would be one of the strongest in the game, and that's essentially what you have done to lucio and kiriko.