People max it second.
It gives a 60% Non-decay MS buff for 1.5 seconds.
A 170(+50% AP) Shield... Just as the base shield.
Her ult now grants everyone around the Speed buff,
and 30% of the value shield goes to everyone near by as well.
That isn't taking in account ardent shield buff (10%), or the mastery that increases it by 5%. And if she so happens to buy a Mikael's as well, she gets even more bonus shield.
So yeah, it isn't just Karma, its shields in general.
But all shield spammers need to actually get timing down on when it is smart to use it, instead of spam, spam, spam, spam...
Edit: You mentioned Lulu in the post, I get it, her shield is higher base amount, and scaling.
It doesn't grant the MS buff, she has to use another spell entirely for it.
It has a 10 second CD all ranks with 6 second uptime. With 40% CDR, always up.
Have we found the common factor? With so much CDR in the game, everyone shields are up near 100% when it comes to supports. That is very unhealthy for the game and has been complained about, not just by the boards, but pros and streamers for a long time.
Reducing shield duration on a global scale is much needed.