In the case of the enterprise solution that will be around for the next 10 years, I would agree with your tech lead.
Every time you make a code change for something that is out of dev budget, you face a budget overrun in the project that was interrupted.
If you choose to deliver something that just works and as soon as possible, your total costs tend to balloon over the lifetime of the system.
Question to ask is: how long would it take for a new dev (someone who has never seen the code) to change the tradeReference naming convention to include the asset type, or some conditional tag, lets say to conform to reporting regulations or even an expanded business mandate?
Interfaces do help here, because the new guy can make a localized change, write a small unit test, and commit the code to source control before you can say "rebuilding search index".
Keep in mind that you do not know if something is well architected until AFTER its been in production for at least a year and had features built into it for another year or two, and has added new members to the team, and has lost a few of the original team members in that time,
I believe that most people who are able to look back and claim that they have delivered at least three large projects (>500k LOC c++ or >200k LOC java) or product releases that meet the above criteria, would agree with your tech lead.