Like coding, selling is also a skill that can be learned through practice.
There is also a difference, in a commerce transaction the best outcome is when both parties think that they got a good deal, how the parties feel about each other only matters in as much as it will impact future potential transactions (i.e. if the buyer thinks that the seller is a sucker and charged too little then as long as the seller is happy with the price the only consequence is likely in the future if the buyer tries to take advantage of the seller)
In a transaction that aims to start a long term relationship (i.e. employment!) ideally neither side should carry negative sentiment from the negotiation. Likely you are negotiating with an HR dept or recruiter who won't take it personally, that makes it easier for the applicant to be a little "harder", the reverse doesn't apply, if the company plays hard-ball it can leave a lingering sense of resentment in a new employee (who should otherwise be entering a honeymoon period)
The last time I changed companies I took a small pay cut (bottom line, headline pay was slightly more, but benefits were noticeably worse) - it grated for a long time, even though the eventual outcome was good (acquihire)
Having been on the other side of the hiring process, I doubt it. Finding good candidates is hard, by the time that you are making an offer you are already much more invested in the candidate as a potential employee than you are in other candidates to whom you have not yet made an offer.
But, (there's always a but!) if you are happy working there, and that's the result you wanted and needed this this was a good outcome for you. Congratulations!
One year later, it's only about as hard as programming, but I'm now on to a new thing that's harder than anything I've done before: managing.
(*or any other recommended book)