Do you think a heal going from 8% heal to 6%, especially having a cooldown is a big change in overall effectivness? I'd describe the original as garbage and the new one as garbage too. All the while tons of other op heals, effectiveness of healing in general get corrected massively.
Don't mean offense, but I don't think what you're suggesting is anywhere near negative enough to compete with the benefits.
In case there would be no limitations/costs to changing spells and efficiency in changing them doesn't matter, your issue could be fine and understandable, but there are costs and efficiency matters a lot for a huge company. Also can't not take feasibility into account.
If your suggested change costs the company more than they get in return while achieving the absolute same, but avoiding 'looking worse' for the players, none of the company's leaders going to support your suggestion. And if they don't, gl.
What you do is, rule out a method for achieving what you'd like, so if they don't want to do it another way, you might not get anything at all instead. It's what happened and still happening with 6.2 in WoD. Did not like Battle Fatigue in beta, so they left healing op and instead combat it by the same way MoP did, by huge burst and high CC.
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EDIT:
Might be good to look at MoP PvP and WoD 6.2, compare them. MoP had 60% Battle Fatigue, WoD 0%, yet I think both are/going to be very similar and could probably describe both with way too high burst and CC in general.
It's because having BF or not, doesn't determine if it's a bad/good game, the very same game of any type can be achieved by the use of Battle Fatigue and without as well. But if Battle Fatigue is the way that costs less, Blizzard is going to prefer it and I think it's reasonable to expect such.
In fact the cost difference can be so much, that unless they can use BF, Blizzard won't even attempt to truly fix PvP issues.
Why the same game can be made with and without Battle Fatigue too is due to this problem.
http://i.imgur.com/PQMyfyt.png