It seems that it wasn't only 'tough times' which prompted the emigration...at least the official line anyway. Freedom also had much to do with it according to this:
To understand why a South American desert could seem preferable to Wales, you have to know what motivated that first party of emigrants, who sailed from Liverpool in 1865, aboard the ship the Mimosa. Very simply, they wanted freedom. These people were Welsh by language and nonconformist by religion. In the mid-19th Century that made them part of the majority in Wales. But the majority didn't call the shots. If you wanted to get on you needed to be English-speaking, and also, if being an Anglican was not an absolute necessity, it certainly helped.
http://www.bbc.co.uk/legacies/immig_emig/wales/w_nw/
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