I have been level freezing and I'm not entirely sure either whether it is worth it, but I tend to lean towards thinking it is. I've never not level frozen so idk what it is like if you don't. However, for me, there are two things that make it worth it:

1) Matsuri is easier. If you don't let the timer go over 1 minute, you will eventually get matched with someone in your level range after a lot of tries. Sure, there are people in the lvl 70-85 range who have like 200k+ power, but in my experience most don't. If I'm patient, I can get at least 3 or 4 wins in Matsuri, which is worth a lot of sun scrolls. If I were like, lvl 95-105, I think this would be harder, because a larger percentage of people in that level range are strong.

2) I don't get plundered because my level is more than 15 below that of people who would plunder me, so it's not really an option. I c*ways run convoys for coupons safely. This may or may not apply to your server. If there are a lot of other people who level freeze, then this might not be as applicable. But where I play, outside of my own group, there aren't many people who could plunder me because of this. So convoys are really stress-free.

Finally, I think there is something of a prestige element to it in my opinion. If people see you're in the lvl 70-85 range with a lot of BP, they'll know you know what you're doing and have been preparing hard from the start. This doesn't really have any impact on winning or losing in the game tho so, it doesn't matter that much compared to the other two things.