Is it possible that connecting Ikea Trådfri plugs to the Hue bridge and then integrating Hue with SmartThings disrupts Zigbee routing within SmartThings?
Alternatively, should the Ikea Trådfri plugs be directly linked to SmartThings to enable Zigbee routing for all my Zigbee devices connected to the SmartThings hub?
possible, but very unlikely. 
Your Hue Hub creates its own mini Zigbee network. Normally this has no issues existing in the same physical building as your SmartThings Zigbee network.
If you think there is an issue, the first thing to do is to check the zigbee channel that the two hubs are using. You can find this in the Hue app under Settings for the Hub, and on the SmartThings advanced page of the web interface to your account.
As long as they aren’t using the same one, you should be ok.
Alternatively, most people have reported that the IKEA plugs are good repeaters on a smartthings Zigbee network, so you can certainly use them that way. There is one exception: some UK members have reported issues with some aqara battery powered devices when using IKEA smart plugs as repeaters. No idea why that particular group was affected, but the models are a little different, so it’s certainly possible. So you can try it and see how it goes.