I agree entirely with your assessment of the situation. Although there is still some ambiguity with the law for 2017, the facts and circumstances surrounding the current environment (SEC guidance, critical reception by taxing authorities) combined with the limited benefit associated with taking a position of like-kind treatment (potential deferral for 1 year in the case of high frequency traders) lead me to the opinion that not using 1031 is the way to go.
To play devil's advocate, the fact that they had to codify the provision suggests that 1031 was available to taxpayers prior to 2018. Assuming that Form 8824 was filed correctly and the criteria of 1031 are met, a taxpayer does not have any specific laws or regulations precluding them from taking the position. Additionally, a taxpayer is at risk of paying more than they are legally obligated to pay if they do not claim like kind exchange.
Overall, I believe the conservative approach is more likely than not the correct position to take.