The difference is that the antenna & bending issues were grossly exaggerated by clickbait reporting and lawyers angling for a class action win. As the wikipedia articles note, neither affected a significant number of users – the iPhone 4's antenna was still more sensitive than the 3GS it replaced – whereas the keyboard issues affect a lot of people. It's not the urban legend-style “my third cousin has a friend who held his phone hard enough to drop a call” reports which characterized those earlier flaps but real named people who are directly affected and getting hardware replacements because Apple techs agreed with the problem.