There are multiple reasons why we add code for setting the correct configure option based on the toolchain being used in the easyblock.

First, the configure option is only determined by the compiler used, not by the full toolchain. So, all easyconfigs that use a GCC-based toolchain should specify `-platform linux-g++-64`, all easyconfigs with an Intel compiler-based toolchain should specify `-platform linux-icc-64`.
Having this repeated across easyconfigs is a nightmare if it needs to be changed/enhanced (e.g., add another configure option next to it) in the future, because it has to been consistently across all easyconfigs. This problem doesn't exists if the easyblock takes care of it.

Also: this way, the easyconfig file remains clean: only the basic information is there (what software (version), which toolchain, ...). The easyblock takes care of all the nasty software-specific fiddly bits that are easily forgotten and (perhaps hidden) break a build.

So, I feel this really belongs in the easyblock...