I would think it is a good thing. The only people this doesn't encourage to buy Switch is people who own a Wii U, and my guess is Nintendo believes it has those 13 million or so customers in the pocket already. A steady flow of games for the system is what Nintendo needs to get people who rejected Wii U on board.
Cannibalising the Wii U library is a quick and cheap way of substantially increasing the game library in a way that will encourage a larger market segment to get on board with Switch. As long as brand new games are released as reasonable intervals I suspect the die hard fans will be happy.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."