Last time I looked Specialized has a triple available on any model you choose.. You may not find it on the showroom floor but they are available. Order it! Call Specialized directly, don't let the local dealer tell you its not available.

To answer some of your other questions: You dont NEED a triple, any crankset will work with both positives and negatives. I use the 53/39 on my race bike because all the other racers are using it, and its nice to match gearing to speed of the group.

My compact double was replaced recently with a triple because I ride long distance events of up to 1200k in <90 hrs, and I travel with it all over the country for events. So 1 event may have 200,000 feet of climbing and another event may have 10,000 feet of climbing over the same mileage. It makes sense for me because I can be Fatigued from lack of sleep and/or not trained for all that climbing. Its versatile, I dont have to change cassettes based on terrain, my 13-25 does it all, my rings are 50/39/24. I stay in the 39 most of the time and only go to the 24 when the mountains get steep.

Your right that triples are getting hard to find but not impossible.. The market is getting small because not many cyclists do the kind of riding I do. I believe triples were originally designed for the weak cyclist or beginner and were usually seen on the lower end bikes. Compact doubles are now working in that arena and it allows manufacturers to cut back on inventory or manufacturing costs.