(I realize I'm responding to a nearly decade-old comment.) Having flown to and from Bangalore many times in the last several years, here's my take. I, personally, when traveling for work, want to minimize commute time to the work location and therefore always find a hotel in the city somewhere. However, more than once I've talked to leisure travelers to Bangalore (from the US, mainly) who quite appreciate having a 5-star hotel right next to the airport for a couple of reason, which I do understand. First, they have read all the lurid headlines about how late-night travel on the airport road to/from the city is risky, with reports of robberies by random people on the highway or sometimes by the taxi driver or Uber driver himself, and high levels of fraud and harassment by taxis - taking you by the Bagalur bypass route to avoid the tolls and then shake you down for money in a desolate area for instance. Unfortunately many arrivals from the US are after midnight, and so are departures to the US. To avoid this, many are willing to pay to stay one night at the Taj at the airport when they arrive, and sometimes also to stay there the day before their departure (most departures to the US are after midnight, 2am, 4am, even 7am) so they don't have to travel on the airport road after dark. Some of the news reports even make me stop and think - and I like to think of myself as being used to most things India can throw at me - a year or more ago there was a story of a "gang" that would place logs or tree trunks on the airport road to force taxis to stop, and then systematically loot the occupants. Or the same done by roving gangs of motorcycle riders who force the taxis to stop. What can one do in such a situation?

Second, it is a really long drive from the airport to most parts of the core of the city! Many don't relish the hour to hour and a half, maybe even two hours if destination on the south side of the city, of driving into town right after the misery of 20+ hours on planes and would rather just sleep right away at the Taj. Can't blame them. If the flight arrives after 2am, and you are unlucky enough to spend an hour getting through immigration and all that, well, you may really want to just catch a bit of sleep when you can, no?