The first time I watched ESC was in 1992. Three countries were allowed to sing in English, and those three made up the top-3 (1. Ireland, 2. UK, 3. Malta). All good songs, but still. This was followed by:
1993: 1. Ireland, 2. UK, 8. Malta
1994: 1. Ireland, 5. Malta, 10. UK
1995: 10. Malta, UK, 14. Ireland
1996: 1. Ireland, 8. UK, 10. Malta
1997: 1. UK, 2. Ireland, 9. Malta
1998: 2. UK, 3. Malta, 9. Ireland
So during those seven years five winners were in English, an additional six podium finishes were in English, and only one song in English finished outside the top-10. The rule had to be changed.
However, I have to agree the current situation is a bit sad. I would be completely fine with the majority of songs being in English, but there's barely a handful of non-English songs nowadays. And some countries NEVER send anything in their own language/languages. Some kind of "soft" language rule (e.g. national language at least every fourth year) would be nice. And stop translating songs that have won a national selection. What the heck is that all about?