You leave out the most important element of these failures with a .243, namely, what type of bullet/load was used?
I've killed dozens of deer with a .243 and never experienced a problem. I used Federal Premiums with 100 grain Nosler Partitions or handloaded 70 grain Barnes X's. The standard hunting rounds will often fail miserably, but that problem is not limited to .243 caliber.
If you want good results (in any caliber) buy good bullets.