A strikingly large percentage of Apple Inc. ( NASDAQ: AAPL ) iPhone owners don’t think that the iPhone 13 introduced last month is a very exciting product. Some 64% say the new iPhone is “not very” or “not at all” exciting. Less than a quarter of an estimated 113 million U.S. iPhone owners plan to upgrade to the iPhone 13. The data is based on a survey of more than 5,000 adult U.S. iPhone owners by mobile device research firm SellCell. Among the 23.2% of iPhone owners who plan to purchase an iPhone 13, the most popular model is the…