There are some good points being made here but also some classic arguments that the LAVs are all white elephants, political, should never have been built, etc.
There are a few things to keep in mind in my view:
1) Historically, and thanks as well to the fact the dictatorship of Franco only ended in the 70s, Spain has been pretty underdeveloped in terms of transport links. Until the first plans for the LAV between Madrid and Seville, many mainlines were slow and often single track. This was reflected in a large number of long distance night trains across Spain - now sadly as with much of Europe gone or nearly all gone.
2) As with all accession countries, matched EU funding has massively helped with road and rail links. Of course there have been some decisions that are not financially viable and arguably you would struggle on paper to make the case for new lines in Spain at all, but clearly given the geography and distances it lends itself to it for the greater good. The two main corridors (Madrid to Andalucia and Madrid to Barcelona) see regular trains and have seen a shift in usage from car/bus/plane to train.
3) More recent and less justifiable projects have been cut e.g. the cross Andalucia line in times in recession. Others completed, but with a single track initially. Other projects still have been altered to save costs.
4) France has also seen a massive cut in conventional services in favour of high speed ones over time (of course that also helps drive the business case as passengers are forced on to such services). Many of the more recent cuts in Spain also reflect poor usage and cost cutting. Personally I wish that wasn't so, but it is.
5) There can be no doubt that as a social mobility project, the high speed network is impressive and opening up Spain in a way that did not exist before. We have Spanish friends that do use the AVE/AVANT etc more than they would have used conventional trains given the time advantage. The only thing to note is they are not by Spanish standards cheap unless you get a promo fare.