I'm very critical of ENO's dogma of translating everything, but I'm supportive of the concept of translation, for some operas, languages and situations, for the following reasons:
1) Smaller productions and venues where a direct communication with the audience is desired, particularly in comedies.
2) Some operas don't contain famous arias, so nobody is going to be disappointed that the tenor didn't sing Nessun Dorma, for example. Do we really need to hear Katya Kabanova in Czech rather than English?
ENO's recent Mastersingers had a wonderful English translation which seemed very singable. It was a pleasure to read on the surtitles, in the way a literal surtitle translation wouldn't be.
Operas/composers/languages I don't like to hear in translation:
La Boheme, Turandot, Rigoletto, La Traviata, other famous Verdi, famous Mozart, and anything with very famous arias.
Operas/composers/languages I really don't mind hearing in translation:
Duke Bluebeard's Castle, Pelleas and Melisande, Jenufa, some comedies, Handel, Wagner, anything Czech, Rimsky-Korsakov, anything obscure. I'm interested in the art and problem solving challenges of the translator. You're welcome to argue these points, but in my opera-going experience I haven't felt I'm missing out on anything when seeing these performed in English.