There's a difference between losing a player (who isn't even crucial to Bayern because they also have Schweinsteiger, Martinez, Thiago, Lahm, etc) because you refuse to offer him the wages he wants than losing a player because you're not a big enough club to keep him. If Bayern offered Kroos the contract he wanted he would still be in Munich, and let's not forget that Real are the European champions. If we lose Vidal to a club that isn't in Europe it's a massive blow for us in many ways. If this happens what's to stop someone coming in for Pogba next season? We need to stand firm, not just because Vidal is our best player, but as a signal to the rest of the world that we're still a big club and world class players still want to play for us.
I think Kroos is/was crucial for Bayern. Hes 24 and world class yet. Thiago is very injury-prone (out till october again) and Schweinsteiger is past his prime. Martinez is a defensive midfielder and not a CM/strategist as kroos and Lahm is a right-back and barely a world-class midfielder.
kroos wage demands were too much for bayern, so he intended to leave. okay, its real madrid, the biggest club in the world, but its a huge loss for bayern anyway, even in a prestigious manner.
ManU tried to sign kroos as well with huge wage offers, there were (reliable) reports in the german media for weeks. anyway, kroos has chosen real madrid in the end...
Bayern dont pay wages like they pay in england (manU, city, chelsea, arsenal), spain (real, barca) or france (PSG).