The value of footer links has diminished greatly over the years. Not worth the effort.
Can it negatively impact SEO? Absolutely. I still hear stories of this. Not as common as a few years ago, but still not impossible. Personally, I had a web design site get a manual penalty for unnatural linking because I would like to my design site from my clients sites, in the footer. I had to edit each clients site to remove the footer link before I could get reindexed. And by then it was too late, I never recovered even though it only took a week or so to remove the links and request reinclusion. This was 4 or 5 years ago though so I’m sure it’s changed somewhat.