The context here is about increasing conversion rate, from website visitor to active, converting user. Or from passive newsletter subscriber to a lead (a user who opens the newsletter, clicks on the links, and converts). Here we will discuss the newletter conversion problem, although it applies to many different settings.
Of course, to maximize the total number of leads (in any situation), you need to use both seduction and analytics:
sales = f(seduction, analytics, product, price, competition, reputation, marketing)
How to assess the weight attached to each factor in the above formula, is beyond the scope of this article. First, even measuring "seduction" or "analytics" is very difficult. But you could use a 0-10 scale, with seduction = 9 representing a company doing significant efforts to seduce prospects, and analytics = 0 representing a company totally ignoring analytics.
In the context of newsletter optimization (to maximize lead quantity and volume), I think most companies set seduction to 1, and analytics to 4 or 5 (in a scale from 0 to 10, with 10 being the best). Analytics is usually achieved through multivariate testing and mathematical segmentation and targeting of user base. I believe this is not the best approach, and that it is caused by the way marketing people are trained. Segmentation by ISP rather than by traditional user group, is now critical. Failing to reach Gmail users is far worse than reaching to Gmail users through a poor user segmentation (e.g. where young and old users receive different messages, but not in an efficient targeting).
Another critical mistake is to use keywords - in the subject line - that work well, over and over, exclusively, until subscribers are so bored that they don't read your newsletter anymore (unless you've found a way to beat churn, maybe by hiring a growth hacker). The problem is compounded if all your competitors use exactly the same wording. We discovered that a rich variety of non-hype keywords work well with an analytic, highly educated, spam-adverse audience. Indeed, a subject line such as 'Weekly digest, July 29' works far better than '25 Fantastic Articles From Top Big Data Gurus'. Sure, the latter will work very well 2 times, but eventually, it stops working. In addition, the content of your newsletter must match the subject line, otherwise you will lose subscribers very fast, much faster than you can acquire new ones.
I believe that my contrarian (anti-hype) approach is seduction 101 rather than analytics 101. Maybe it can be automated and turned into analytic rules - e.g. by detecting how many times you can use hype, how long a great keyword such as 'belly dancing analytics' will work, etc. But for now, marketers still seem to ignore these basic rules of seduction. Seduction can provide a bigger lever than analytics (althought they should be blended together), especially when building a business for the long term.
To summarize, your prospects react like cats, not like dogs. If you treat them like dogs, you will underperform.