There is only one thing better than being able to speak a foreign language – being unable to speak a foreign language.
In the first instance you can take your linguistic skills to said foreign country and participate in the life of the common people. You will not be restricted to hotel staff and major stores in major cities. You will be able to find where the locals eat and where the toilets are and you will be able to catch public transport without fear of unexpectedly ending up three cities away.
On the other hand, the local people generally live far less well than the hotel…and the markets, food, and general experience that they undergo might be hellish. The toilets you find may be one step ahead of finding you. And riding the local minibus rather than a taxi may be hazardous to your health – you can get robbed and beaten as easily by a person whom you can understand as by one who is speaking gibberish.
Now if you do not have any of the local language, you do not have to understand or react to casual insults or demands for money. No-one can force rugs or bracelets on you if they cannot make you understand the words for rug, bracelet, or pay. You can shamelessly utilise English-speaking guides and couriers provided by hotels to do the simplest of communication tasks.
Of course you can still be made to feel uncomfortable by gestures and behaviours, but as you do not comprehend the words, insults lodge in the mouths of the speakers. You miss out on cultural performances, but remember that all cultural performances are not necessarily elegant or sophisticated – every nation has a Kath and Kym somewhere.
Be particularly careful if you are feigning ignorance that you do not let on that you understand any of the words. Do not be tempted to return snide fire with snide fire, unless you can do it in a language that is so far removed from where you are that no-one will twig. Best combo: speak Inuit when in Indochina and Navajo when in Japan. Smile, nod, and sound polite while calling them slimy walrus turds and you will probably get away with it.
Note that international traveler’s signs are pretty universal – you can travel on the Tokyo trains without getting into too much trouble. And I suspect that they can travel on ours as easily.