I don't think the suggestions are bad per se. The reason they come across as condescending is because they're obviously very generic and they're sent to people who, in the current market, can be picky about who they want to work with.

Ultimately your whole business model is competing with tech recruiters, and my recruiters will call me to give me feedback from a role application, you have reduced that human touch aspect to an email with a few links to hackerrank.