Sam said:
.Pro is bad as .AERO. Top million names = brand awareness. IMHO, this extension is dead.
allinurl: pro.com in Google = 1,560,000 uniques
allinurl: aero.com in Google = 18,000 uniques
allinurl: mobi.com in Google = 22,100 uniques
allinurl: biz.com in Google = 299,000 uniques
allinurl: info.com in Google = 3,810,000 uniques
allinurl: org.com in Google = 553,000 uniques
allinurl: net.com in Google = 7,060,000 uniques
allinurl: tv.com in Google = 10,600,000 uniques
allinurl: me.com in Google = 938,000 uniques
Conclusion = Developers add Pro to keywords in .com because it's brandable.
pro in US trademark database uspto.gov unpunctuated marks = 15,131 marks
aero in US trademark database uspto.gov unpunctuated marks = 874 marks
mobi in US trademark database uspto.gov unpunctuated marks = 123 marks
biz in US trademark database uspto.gov unpunctuated marks = 790 marks
info in US trademark database uspto.gov unpunctuated marks = 1,101 marks
org in US trademark database uspto.gov unpunctuated marks = 1,060 marks
net in US trademark database uspto.gov unpunctuated marks = 7,731 marks
tv in US trademark database uspto.gov unpunctuated marks = 5,478 marks
me in US trademark database uspto.gov unpunctuated marks = 7,870 marks
Bear in mind that org and net trademark results are skewed if you are analysing inherent brandability because half of their marks are actual .org and .net domain names.
Conclusion = Business owners trademark Pro more than they do any other alternative extension. The suffix Pro is inherently more brandable than any other domain extension. In fact, it's more brandable than .mobi, .biz, .info, .org, and .net added together.
If .pro featured prominently in that list, the top keywords would cost hundreds of thousands of dollars. The whole point of investment is to second guess what will feature more prominently in 5, 10, and 15 years. If .pro restrictions were removed, it would, without a doubt, feature far more prominently because it's more brandable than any alternative to .com, it has a wow factor, and fits a broader spectrum of keywords.