The biggest source of sadness is going to be AoE-related. When Bard had DoT-based procs, you could spam DoTs on enemies while the mobs were gathering, and then once the pull was ready for AoE you got a crazy downpour of procs and soul gauge that was super fast and hectic and fun.
However, many people disliked the setup required - the idea of using single target DoTs in AoE offended them somehow. There were many many asks for a Bane equivalent, for instance. But this setup time was the only thing arguably keeping that AoE kit fair. Even then it was still grossly overpowered, frankly. So it's sad but not surprising to see it gone.
What's more disappointing is that the decision was made so last-minute that SE couldn't construct a replacement kit that felt particularly good - it's a mashup of skill shapes and natures that don't work together very well, making you swap targets like mad if you want to try and make the best use of everything.
This sort of cursed nature is the only thing making it at all interesting, to boot. On its face, the actual AoE skills are just a 1 - 2 where the 2 has to be proc'd, a single AoE oGCD and a really slow meter. The rest of what you're doing is finding things to point Empyreal, Sidewinder and Pitch Perfect at and shuffling targets to suit your cone vs. small circle vs. line aoes.
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As for single target, you're going to get some missing of the potential for double procs, but as much as anything it's irritation over things Bards liked from the media tour that got the axe - 90s flexible Radiant Finale, 30s Blast Arrow duration, 60s Raging Strikes cd, and Army's Paeon still affected song cooldowns for a touch of flexibility (though that's funky and I agree with killing it, but it needs a replacement).
Mage's Ballad getting nerfed is probably the single biggest sticking point. It's now weaker than Army's Paeon, so it's become optimal for players to spend a full 40+ seconds in the much-maligned weakest and most boring song.
Also, while ShB laid it on a bit too thick, many had a fondness for the sense of pressure MB gave to react to procs quickly as it made the song highly engaging. Three charges + half-procs wipes that out entirely. This is probably for the better in an overall player population sense. But those who liked that about Bard, would have preferred something like three charges and full resets, or two charges and half resets just to still have some of that dynamic still around.