Having played through the 39 campaign now, I have a better feel for the design intent. There is indeed a lot more combat result variation than prior PGs.. leading almost inevitably to losing core units (at least for me.. I play "iron man" and accept losses). But the compensation for this is that initial experience is gained very quickly and experience plays less of a role in the combat results (it seems). Therefore, losses are an inevitable part of play but are compensated for quickly. So in this sense more random results is "ok" and encourages accepting losses, which is more "realistic" than the old PG.
The problem here is that you usually attach more to units which annihilate everything in sight. If unit's performance is average, you will not attach to it, even if it has a pile of medals, heroes and combat history on it. But overpowered units are bad for game balance. This is exactly the reason why they do not exist in PzC. Not because it is more "realistic", realism is not an utmost concern in this kind game.
The role of experience in PzC is complex. On one hand, you can probably play with green units only, especially on lower difficulty. On the other hand, experience allows you to pack more punch into the same number of core slots (which is always a useful thing, especially on harder levels like Manstein), and at the same time it serves as a prestige sink. If you have a lot of prestige, it is unwise to use green replacements. If you are low on prestige, green replacements is all you can afford. Both strategies are viable, and every player finds his own balance between green and elite replacements. I think, this is the right approach. Your core will not be crippled if you cannot accumulate enough experience. And it will not become overpowered if you do get all 5-star elites.
The downside is I find I am less attached to units because there loss is less vital and their experienced status is less vital. I also find the "heroes" rather boring compared to the old "Leaders" in PG2 with their rather unique effects. Those "Leaders" also increased the sense of "value" of high experience units. More so then one stat add due to a hero.
Marketing does amazing things. Most leaders in PG2 were also stats-changers, but thanks to fancy names like "aggressive attack" and "tenacious defense" this was not so obvious. ;) As for leaders which did have fancy abilities, many of them destroyed game balance too.
p.s. I do think removing the overruns was a mistake, they made for interesting tactics and a different feel to tanks. Right now tanks just seem like one more "rock paper scissors" element... well not entirely but they don't seem terribly different from other units. I find I am doing fine with just one armor in my core often!
Even though PzC and PG2 are very similar on the first glance, they are different games. From all you have said, looks like for you PG2 is a better choice. ;) But it does not mean that PzC is worse and must adapt elements from PG2 to get better.