What a polarizing topic! I'm an avid wine drinker/collector and I think if it's a white wine that made to be drunk within 5 years of production, then put a screwcap on it by all means if it will save money. However, screwcaps are not a panacea, as mentioned earlier, for ensuring quality.

I prefer drinking wines with 20+ years of age and do so regularly therefore I'm extremely hesitant to advocate the use of screwcaps on bottles I intend on aging. I haven't yet tried a screwcap wine from the 1980s or before. When I last visited one of my favorite American wineries, Ridge Vineyards, I discussed this topic at length. They do blind tastings of their bottles with cork and screwcap on a regular basis and consistently prefer wines enclosed with a cork. So I will fully support their decision to use that going forward.