No, using the LGPL code done by third party is still free of charge.
> This is a "coopetition" among companies and everyone benefits from it.
And we also have seen many times developers who released their code as MIT never seeing a dime from these big companies (such as Corejs developer).
LGPL is the way to go to ensure that big corps who make money out of an open source project do pay up. You don't want to release your source code? Then pay for a commercial license, end of story.
Right, of course; hence the failure of Linux and the dominance of the BSD family. /s
But yes, using permissively-licensed components absolutely is* a good thing, including for the users, who get higher-quality software with less dev time and lower cost of development. Obviously I'd prefer that it was all GPLv3, but given that the alternative in practice is probably fully-proprietary software from scratch, I think BSD is better than nothing.
OpenCV (and many other open source frameworks) never had a CLA so this wouldn't be an issue for that. In my opinion there is nothing inherently wrong with dual-licensing but it's expensive and many companies do not have the resources to pull it off correctly. Re-releasing under the BSD license appears to be the backup plan if the Qt Company ever goes belly-up.
It significantly hampers cooperation. No company in its right mind would make a large investment for free in the development of software sold by another company. Without this unspeakable dual license, a balance is possible, i.e. the companies can invest and use without taking inadequat advantage of each other.
In the event of total failure of Qt's business model and reversion to a BSD license it is also very likely that there will not be much left of a market for big enterprise services around this type of product, so be careful with that double-edged sword. You might just end up with more fragmentation and internal proprietary forks to contend with. On the other hand, independent consulting will always remain an option as it is now.