It is unlikely you'll ever regret fitting a good ground anchor and upgrading your chain and lock. You may regret not doing it, especially if you think you should. I kept thinking I should bolt up the bottom of my garage, and only did after some toe rags stole my mtb. Guess how they got in?
Spending at least whatever your insurance excess is is a good rule of thumb. If that sounds a lot, if the bike does go you'll lose that much money immediately, have to find another bike and upgrade your security aswell. That's not just money, but time, hassle, and lost no claims bonus.
Almax do some good chain, lock, anchor combinations for various needs. Highly recommended.
Oh, and if it was me, I'd be inclined to beg forgiveness for installing without asking, rather than asking and getting an answer I didn't like ;)
Sounds like it wouldn't be causing an obstruction where you park, and you're only following their advice....
Good luck.
Good on you for the offers of assistance folks.