On the contrary I think it should be as easy as possible to fork, and for such forks to be as non-disruptive as possible in the case of a contentious change. When there is a split, not only do individuals need to decide what they see as valid or more worthwhile going forward, but exchanges and ecosystem infrastructure need to decide what gets to be considered to be the same token, with the same brand.
In a truly contentious fork, eg. if Bitcoin XT, Bitcoin Classic or Bitcoin Segwit2x had forked as originally planned, both camps may be claiming to be the 'true' Bitcoin at the time of fork, rather than ceding with a fork rebrand as in Bitcoin Cash or Hive. In this case the ecosystem of exchanges etc. need to make a decision fairly quickly as to which network gets to be 'Bitcoin'. Regardless of which side of the debate they actually lie on - exchanges need to go along with everyone else, or we end up with a situation where Binance is selling tokens on one chain as "Bitcoin" and Kraken is selling "Bitcoin" on another. Formalizing the consensus rules as happens in layer 1 allows for easy schelling points upon which people can make these decisions, generally avoiding the undesirable situation.
Layer 2 applications could formalize rules to decide what is 'valid' in the event where a change to the rules is necessary, but they generally don't. In the absence of it, the default is for the developers (or even just the person who owns the website or code repository) to be the deciders, which gives them special control and authority on the network. That is what makes me uncomfortable with layer 2 applications. While I can decide if I like the rules of a layer 2 system as is, I have no way of knowing what the rules will be in a year, and no way to be confident that there is a way for the community to come to consensus on it.
I agree that Tether is centralized but I disagree that it doesn't show the point. It wasn't just Tether that forked, it was the entire Omni protocol. At the time of the fork there were over 300 different asset definitions on Omni and they ALL had to fork to the new version. Tether simply had so much weight that it forced the issue for everyone. In the absence of any other way to make the decision, everyone had to go along with the developers choice of what was now the valid rules for Omni, which included the possibility of tokens being frozen by asset definers.
I have yet to see a layer 2 system where the developers don't have the weight/clout to change the rules on their own, where their application is used so much that it will be the default accepted by exchanges in every change that happens, regardless of what the community wants. I'm not saying it's unsolvable, but it's how L2 systems typically are today and there's no pressure for that to change.