The Tour de France peloton used to use fixed gear, but you don't see Chris Froome riding one of those bikes...
Yes, you can get low gears without needing lots of them to choose between. For years, I used 9-speed 14-28 cassettes so I gave up 2 or 3 higher gears to get lower ones. It is quite nice to have some high gears available though for those luxury rides down gentle descents with a tailwind...
Yes, you can get a wide-range cassette without extra gears but then you have big steps between gears, which may not suit.
Ability to get a 12-36t rear is my only reason for going 9-speed.
My 2x10-speed CX bike has a 12-36 cassette on it but I find the steps between the bigger sprockets too big - one gear feels too high, the next down often feels too low.
My 10-speed CAAD5 now has almost the perfect gearing for me after I converted it from a double to a triple chainset. I use a 12-30 cassette (steps between gears not too bad), and 48/36/28 chainrings. The 48/12 top gear is high enough for me 99% of the time, and it doesn't hurt me to freewheel if I am going faster than my spin-out speed of about 60 kph (37 mph). The 28/30 bottom gear is low enough for me 99% of the time, and it doesn't hurt me to walk for a couple of minutes about once a year if I come across a ramp much steeper than 25%. The steps between the rings are nice and tight too. The big ring is small enough to use quite a lot on flat rides (as opposed to my old 53 which was too much like hard work). The middle ring is perfect for most of my riding - I can ride at my normal maximum speed using it, but it can also give me low enough gears that I don't have to resort to the little ring for short steep climbs. The little ring is always available for the terribly steep stuff, or long climbs at 10+%.
