It is not a forced equipment upgrade. You chose to download the iOS without checking its compatibility.
Your equipment has not been manufactured for 8 years.
Just because your device is compatible now, adding new system wide software should never be expected to allow it to be compatible indefinitely.
You can still buy on the open market iPad 1, 2, and 3 that have not been upgraded to iOS 6 or later.
Just not from Apple directly. As long as you do that, and do not upgrade to iOS 6 or later, you can connect the iPad to a PowerPC G4 867 Mhz or faster PowerPC Mac with a powered USB 2 card.
The writing has been on the wall.
Powerbook G3 (from 1998) with no USB can't upgrade past 10.2.8 (from 2003).
Powerbook G3 with USB (from 1999) and no Firewire can't upgrade past 10.3.9 (from 2004).
Powerbook G3 with Firewire (from 2002), but under 867 Mhz can't upgrade past 10.4.11 (from 2007)
Powerbook G4 from (2005) can't upgrade past 10.5.8. (from 2009)
MacBook CoreSolo or CoreDuo (from 2006) can't upgrade past past 10.6.8 (from 2011)
Use Wikipedia and http://www.everymac.com/ as your resource and you can find all this information out.
Google support.apple.com you can find more info too.
Point is there is a maximum OS for everything.
My iPad 1 (from 2009) can't even update past iOS 5 to iOS 6 (from 2012).
Unless you plan for obsolecense, you will be caught by surprise.
Yes it can help productivity if you keep the entire widget up to date together, or if you just keep everything status quo. The myth that you have to update anything though is still a myth, until you get new equipment.
Then you need to keep everything in sync. Otherwise it just won't work. Demand application developers write for older iOS and operating systems if you want to keep your older equipment. Otherwise, any new software you get will have to come with new hardware across the board, or there will be some disconnect.
Many people still have their 20 year old Macs and are still productive. How? They haven't needed any software that their Mac can't run. It is only when you need to keep gadgets together that you become a tinkerer.
So rethink your strategy. Find software and hardware that works with what you have. Don't assume new stuff will work if you must keep old equipment around.