You said, "a lot of people with phantom's are having them" Can you cite your sources for these claims? Also what is "a lot"? Remember, if you're referring to FB and forums people usually only come to those looking for solutions to problems etc. If you see a reoccurrence of a problem several times in a short period of time it could indicate a genuine issue but a random problem now and then is not even remotely "a lot" on an online group/forum. You need to quantify such a bold remark.
I've got a P4 with hundreds of HOURS of flight time and many MILES of Flight and other than the occasional battery merely losing performance (which is expected, batteries are a consumable item) I have had no battery issues. Even with "marginal" batteries we don't see the aircraft "dropping from the sky" but reduced "punch" and reduced flight times" which in turn would lead us to remove a battery from Flight Duty (save it for bench testing, updates, and use as USB power bank) but that's just a Best Practice situation derived from paying attention to your batteries long-term and seeing a TREND in declining performance long before you push the battery to the Failure Point.
From a very fundamental standpoint DJI batteries are indeed "just lipo batteries" and if you don't treat them properly they will FAIL "just like lipo batteries" do. Unless you got a bad production set of batteries it's all about how you USE and how you CARE for your batteries. Even with the "Smart" aspect of the battery you can still do things to shorten their life and greatly reduce their performance while still operating "within the SMART allowance" of the battery.
You ask, "Why not a concern?". That's because on this forum and the Phantom Pilots forum we aren't seeing what you're reporting. While there are occasional battery failures they are almost always the fault of operator error when the facts are presented in detail. How you treat your batteries during storage, flight, charge, and all other times will have a significant effect on overall battery health and then of course battery life. Battery health is almost always a direct indication of Battery Care.
I'm not saying adding a Parachute to your P4 isn't a good and very cool idea I'm just saying I believe battery failure is a LOT less of a problem than you state it is. Of course any problem that affects you (or me or John Q. Public) directly is a BIG problem that's merely because of perception and not an actual massive problem in the big picture.