Plants are indeed controversial in some respects. A plant can remove some of the ammonia as food and can easily make good use of nitrates. That means that the chemical measurements can be a bit harder to interpret when plants are present. The plants may also bring some of the beneficial bacteria in on them so all about them is not negative, plants have surfaces after all. Another factor that makes people not like plants during a fishless cycle is the lighting needs of the plants. Since plants demand lots of light, you may have a problem controlling algae. High light and nitrogen really encourages algae to grow. The low levels of ammonia that we use in our tanks, at only 5 ppm, will not harm plants.
Lots of factors to consider when deciding on using plants or not, the simple answer of use them or don't is just that, it is too simple and misses the fact that you and I may have very different opinions on the value of plants and the negative aspects of dealing with algae growth. For me the algae control may be too much work to even consider while for you the pleasant appearance of a planted tank may make the work seem worthwhile. Plants are a personal choice, there is no right and wrong.