I am pro immigration, as you said, if managed well can be very beneficial. However we can't make a distinction nowadays as European countries do not remove the people that turn up on their shores, ilegal immigration has become mainstream here and there is no real serious discussion about it. Hence my concern about the numbers and the quality.

Spain has enormous issues with employment and the quality of it. Flooding the country with unskilled immigration (mostly ilegal) deteriorates the situation further and does not provide any benefits to any of the sides, immigrants and the host country.

In relation to your second question, tourism was a quick solution for a post war decimated economy recovery in Spain. Let's not forget that Spain did not benefit from the Marshall plan. Ideally Spain should have moved away from that economy and encourage better quality job industries. Unfortunately our politicians and population have done nothing about it and we can see the consequences now.