I won't argue against what you are saying, though I have to admit that I kinda enjoyed the experience at all stages. It always felt to me like I was stealing wins, beating opponents that had way better cards than myself.
The core problem IMO emerges from the upgrade concept. It's cool in theory, but it is a huge issue regarding how people feel about it. It's one thing to be beaten by a better but different card (which is common in any trading card game) but loosing a game simply because your opponent had a higher version of the very same card feels ten times worse.
The larger the playerbase gets the better the situation should become, with people competing on a more even playing field. Ultimately, Splinterlands will have to cater more to new players/players will smaller collections. Only if the game feels worthwhile in all stages it can hope to grow and reach the mainstream market.