Research suggests 1 minute blocks could be fine. What are they missing?

The paper: On the Security and Performance of Proof of Work Blockchains https://eprint.iacr.org/2016/555.pdf

I have not read the paper in details so I may be wrong in my interpretation.

I am not so familiar with Bitcoin or the scalability debate. Can someone explain to me in simple terms what are the downsides of decreasing the block interval?

Assume we have 1-min blocks of 1 MB (with 10% of the current reward). Then,

• is it true that the max throughput would increase to about 60 tx/s?
• the stale rate would increase, the paper suggests the stale rate would roughly double. what are the security implications?
• would the network be less secure? For instance, is waiting for 20 1-min confirmation better or worse security-wise than waiting 2 10-min confirmation ?