Open, documented, standard formats lasts forever.
Closed, undocumented, propietary formats lasts until their creators/owners say otherwise, or die/go bankrupt.
Lossless compression is used for archiving, and archiving is supposed to stand the test of time.
Hence, by this definition, to choose a closed format is unwise.
If you backup your data in something, which in 10 years you won't be able to access, no ease of use today will make the data come back at you tomorrow.
Besides, not adding support to a program for open source formats is plain lazyness of the authors of said program. But of course, if you used a free open sourced program, you could have added it by yourself on the first place.
This only means: If such or such feature does not exist yet, someday it may be added in the future, in the case of open source only. In the case of closed source, you will never now, if it will ever be.
If the author of EAC dies tomorrow, there will be no more EAC. But there will always be CDex, even if the author of such utility died too.
Authors/Organizations can also change their minds, drop projects without further advise, no need to die, maybe just switch business, selling themselves, going backrupt, taking a break, changing their way of life, etc.
Hence, Propietary software is not safe either.
This is only a part of a view of the matter. Free software is more important than you may think. The future depends on it