(Reuters) – JetBlue Airways Corp’s $3.6 billion bid for low-cost airline Spirit Airlines caught Wall Street off guard on Wednesday, with analysts questioning the benefits of a merger between the two carriers. Though both carriers have a fleet dominated by Airbus SE, any potential cost savings from the deal will be diluted as JetBlue would need to bump up the pay of Spirit pilots, who are on a lower band, Raymond James analyst Savanthi Syth wrote in a note. JetBlue said on Tuesday it made an unsolicited $3.6 billion bid for Spirit, at $33 per share, potentially derailing a $2.7 billion merger p…