I disagree with you. As a Ying main, I can say that Resonance is her best talent, the one talent that makes most impact when played correctly. I would actually love Resonance to be a part of her kit as it is honestly extremely powerful and i could pick up Focusing Lens or Lifelike if they brought it to be godlike. Resonance is too powerful to be in her base kit.
Resonance is not a beginner-friendly. It is confusing, and you cannot learn Resonance quickly with a few matches. It takes a lot of time to completely understand how Resonance and Dimensional Link work together to burst heal and burst dps. You can detonate 3 illusions at the same time, which this also means 1200 burst heal. The subject is not Resonance here, but know that Resonance when played correctly has the highest impact and highest rewards. I outhealed many other healers (I can proudly say i outhealed life exchange yings) and outdpsed other damages at the same match. Focusing Lens is easy to get into and rewards the player with aim. Playing safe with Focusing Lens is often better because the reward you get is almost the same with aggressive play. Life Exchange... honestly is terrible, i wish it never existed. It makes other Ying players, especially Resonance look very bad when they aren't. But in all honesty, Life Exchange doesn't teach about Ying and takes one of your best abilities, Shatter, away from you. I see GM level 99+ yings that still dont know how Dimensional Link works... Life Exchange just takes away your multi-tasking ability, one of the best thing Ying can do. You basically become another Seris, but Seris has better escape ability and survivability with Rend Soul. She can even get CC or more max dmg/hp depending on the talent she chooses. Resonance on the other hand, rewards aggressive play. Safe play with Resonance is often a disadvantage. The comboes you can do with Resonance and her base abilities are insane, and it takes lots of practice. Resonance isn't easy to get into or to master. However Life Exchange and Focusing Lens is.
I think implementing Focusing Lens in her base kit with decreased power (like maybe 150 or 100 extra damage?) would be a better idea as it doesn't give any bonuses to Ying other than fast ultimate charge (which Resonance can definitely out-charge, ofc when used correctly) and more damage. So implementing this into her base kit will both not be over-powered and allow high skill/high gamesense players to get more rewards with basic talents (Like Life Exchange). Bringing back Lifelike would be amazing, it was one of my favourite talents.
Note: I'm not ridiculing or saying that Life Exchange is bad, it just doesn't suit my playstyle of Ying. It can be a powerful healing tool. And using basic/simple talents is definitely okay. Complex Talents > Simple Talents is wrong. Complex talents usually give more rewards but they are harder to master and mistakes put you in disadvantage so they are equal overall.
What I would suggest for Ying rework;
-Make her illusions heal 350 every second instead of every 1.6s (it is not actually 1.6s, it is 2.1s because there is a 0.5s shooting time. So even with 1s, it will become 1.5s). This will make her illusions heal more consistently.
-Reduce Life Exchange shatter burst heal from 700 to 600 (because over-time her illusions will heal more so to balance heal outcome it has to be reduced). Or make the shatter-burst-heal become a heal over time, like Mal'Damba's that heal 700 over 2s.
-Implement Focusing Lens into her base kit, with 100 extra damage (so she does a total of 550 damage).
-Re-add Lifelike, with either 25% or 20% reduced heal, or add a new talent. It doesn't have to be about healing, it could be about another aspect about Ying, maybe a talent for Dimensional Link or something like that.