I'd imagine that for most Bass fishing one doesn't need all the amazing side, down imaging. Sure it helps, but most bass fishing is done fishing sight cover, stuff you can already see. Now for deep fish during cold months, finding deep breaks, deep stump fields, etc. probably helps, but then again, so does my 12 year old Eagle unit that I can find on Ebay for $120 now. GPS, etc.
I'd also guess that a fairly decent number of the boats in the big tourneys have gear that was given or loaned to them by sponsors.
They are, as GEO said, a tool. Some people get into a sport for the sport itself, some for the periphery such as the gear. I am a photographer, and I can tell you from experience, it's not always the dude with the most and newest gear in his camera bag that takes the best photos.
Everyone enjoys things differently, and for some, having the newest gadgets, sweetest boat, etc is the fun of the deal, not me, but some. Keeps the pseudo economy rolling I guess.