The industry has standardized on <filename.srt> and just about every player out there supports this. XBMC/Kodi has chosen a [superior] alternate format of <filename.lang.srt> which noone else supports. It really is ludicrous to expect the rest of the industry and all the players to change and support this format. It just isn't going to happen.
Regardless of being more complex or not, every toggle and option within XBMC/Kodi requires additional complexity to support multiple options. This is a choice that breaks subtitle use for every other player. IMO it should have been a no-brainer to add the option for one or the other or both and accept the additional complexity to the code.
In the meantime, a quick cron job script takes care of it for me but it sure does suck to have to create this hack because my preferred media player decided to make a nonstandard subtitle naming choice...
# This will rename a subtitle.en.srt file to subtitle.srt. The .en.srt files are downloaded and renamed by XBMC/Kodi but EVERY OTHER PLAYER needs to have just .srt files.
IFS=$(echo -en "\n\b")
for i in $(find . -name "*.en.srt")
NEWFILE=$(echo $FILE|sed -e 's/\.en\.srt/\.srt/')
mv "$i" "$DIR/$NEWFILE"