Interesting thought!
Polkadot is an integration layer between many blockchains. Thus, by connecting with Polkadot, we might gain a much broader integration basis with other chains that are already integrated with Polkadot in one go. This is definitely something that we should discuss further!
Direct integration without intermediaries requires one crucial functionality: Threshold signing. Only with this functionality one blockchain can create transactions for another blockchain without a (trusted) intermediary. Anything else you need is a (maybe rather complex) implementation effort to get the communication between the two chains going accordingly.
I would not claim that no one else in the world can do this. A few others have attempted this already, but to the best of my knowledge there have been security issues with their threshold signing algorithm or implementation thereof. Threshold ECDSA is a hot topic currently with lots of efforts going on.
I would also claim that it is not feasible for the IC to build a native integration for every other blockchain around. In my view, we will have Bitcoin and Ethereum natively integrated and others via the more traditional approach of using bridges.
There is a nice effort ongoing by Psychedelic (formerly Fleek) of building an ETH ↔ IC bridge called Terabethia:
- Terabethia: Bridging Contracts & Assets Across Ethereum and the Internet Computer 🌉 | by Terabethia | Terabethia | Medium
- https://terabethia.ooo/
This will, in my view, be an important booster for DeFi on the IC as it is the first broad integration with Ethereum and allows for transferring tokens over to the IC. Thanks to the team at Psychedelic for this great work!