Ironically, second time I'm typing this because safari crashed and I had to reload everything!
Anyway..long post..
I'd like to see a screenshot of OP's Safari usage to back up the claim. Posts like this need backing up. Nothing against you OP, but so many wild claims get made, that people start to doubt.
I personally think it's a very valid claim.
My safari usage so far in the 2 weeks of owning my iPhone 6, is 397mb. I haven't used it much, because at work I use my laptop, at home I use my iPad. If my iPad Air was using my mobile data when browsing, I'd be as concerned as OP due to tab reload on that.
According this this site:
http://www.websiteoptimization.com/speed/tweak/average-web-page/
Average size of the top 100 websites, is 1612kb.
The top 1000 is 1622kb, and top 300,000 is 1829kb.
Now assuming you only browse those top 100, 5gb data (5,242,880kb) in a month, would be 3,252 page views.
Divide that by 30, gives an average of 108 page views per day.
That's not a lot if Safari is your main used app, and accounting for reloads.
If I browse Facebook, I may jump to about 4 different pages in one session. Be that articles, statuses, or other people's profiles. I tend to view one at a time though, then resume scrolling through the newsfeed.
If I was reading an article, I'd load a link in the background so I don't lose track in the article. I'd then go to read the pages I opened in the background.
So if safari is reloading at 4 tabs, that 108 page views can actually be only ~30 accounting for reloads. That's only 4-5 articles with "research" and a couple of Facebook browses.
OP shouldn't have to change their browsing habits to account for poor handling of ram (or lack of it, if you wish to take that path).
Especially when companies advertise data allowances in terms of "### web pages" and "### emails".
My only suggestion is also a workaround, using another browser. Which we shouldn't have to do.
Also worth trying the "reset all settings" once in a while, which has sometimes helped clear up tab reloads for me on my iPad Air (until the issue comes back again).
TL;DR
5gb browsing top 100 websites (at 1612kb a go, average), is 108 page views a day. ~30 accounting for tab reloads.