My problem with dispensationalism is their doctrine of the "parenthesis" Church, that the Church is an interruption in God's plan for Israel. That is unScriptural doctrine in my opinion!
Then of course there are the hyper-dispensationalists who seem to believe Paul is a reincarnation of Jesus Christ since they are hung up on Paul's Gospel even though Paul clearly says:
Romans 1:16
16. For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.
I am not a big "rapture" addict, but calmly anticipate the Lord's preserving from the coming day of wrath be it in sleep or in catching away. I really don't care - I just long to go home. More so every day.
More to the last part of your statement, you are correct about "parenthesis" teaching (which I have not been a big fan).
The plan of salvation is unchanged from the beginning of humankind.
What I perceive is that God once somewhat ignored the gentiles, occasionally using them as a tool to punish, and redirect the people called by His name.
Did not Christ reflect the way Jews considered gentiles by calling the woman a dog?
Did not Peter have to be "reeducated" in his thinking?
Was not Paul known as the apostle to the gentiles - though most apostles went to gentile nations and were martyred?
Did not the first major conflict arrive as a result of gentiles believers and what Jewish "laws" they were to follow?
My point being that the "parenthesis" is a very unfortunate wording and often misdirected teaching.
What should have been really taught (in my perspective) is that now, in this time, the gentiles are no longer
excluded but fully
accepted as heirs just as much as any of the root of Abraham. This is as the first church of Jerusalem published by their decree about the Jewish laws.
Of course the danger comes when one desire some greater claim - and "punish" the Jews as a result of some superiority thinking. History is full of this sort.
Paul deals with that sour stinkin-thinkin in Romans, and rather harshly. Showing that Israel is not rejected, but the gentiles are the ones being grafted into the plan now, too.
When one does look at the prophetic structure concerning Israel, coupled with the statements of Christ in Matthew (beginning in 23), and those of Paul (Romans 11) and of John (Rev.) Israel is never out of God's eye, but will all be saved (blending both Jew and Gentile believers into one unit and one assembly).
The "parenthesis" teaching that I heard was sloppy and unfortunate.
Let the readers understand, I do not hold that the Church replaced Israel - that thinking is just not Scripturally sound (actually less sound than the "parenthesis").