Advantages for cycling suppliers
-- won't lose as many customers who give up because "shifting is too hard"
The common complaint is that the customer can't figure out how the relationship between the front and rear DRs (large ring in the front is hard, large ring in the back is easy). Your solution will add more complication.
In asking for 30 (or 27) effective gears you are asking the manufacturer to eliminate cross chaining + a re-design of the RD cage (able to handle large-large and small-small front and rear gear combos). This would take a fundamental re-think of the entire drivetrain. The only option that comes close are internally geared hubs.
With SRAM's new 11-32, they can come close to the gearing range of a stock triple.
However the cost is a heavy toll on shifting timing and rider dropping out of desired
cadence range to a lower effective range. Naturally as the rider works to return to
their natural range, there will be a spike in power generated and a decrease of
energy reserves.
Another fundamental (marketing) issue: Why is the casual rider concerned about their power output? They will just go more slowly, problem solved.